57 results on '"Joonwoo Bae"'
Search Results
2. Radar Elevation Angle Correction Using Parabolic Equation Method
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Jun Heo, Young-Kwang Seo, Min-Kyu Park, Joonwoo Bae, and Yong Bae Park
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- 2022
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3. Measurement Crosstalk Errors in Cloud-Based Quantum Computing
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Seungchan Seo and Joonwoo Bae
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Quantum Physics ,Computer Networks and Communications ,FOS: Physical sciences ,Quantum Physics (quant-ph) - Abstract
Quantum technologies available currently contain noise in general, often dubbed noisy intermediate-scale quantum (NISQ) systems. We here present the verification of noise in measurement readout errors in cloud-based quantum computing services, IBMQ and Rigetti, by directly performing quantum detector tomography, and show that there exist measurement crosstalk errors. We provide the characterization and the quantification of noise in a quantum measurement of multiple qubits. We remark that entanglement is found as a source of crosstalk errors in a measurement of three qubits., 8 pages, 2 figures, To be published in IEEE Internet Computing
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- 2022
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4. Single-Copy Certification of Two-Qubit Gates Without Entanglement
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Yujun Choi, Tanmay Singal, Young-Wook Cho, Sang-Wook Han, Kyunghwan Oh, Sung Moon, Yong-Su Kim, and Joonwoo Bae
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Computer Science::Hardware Architecture ,Quantum Physics ,Computer Science::Emerging Technologies ,FOS: Physical sciences ,General Physics and Astronomy ,Hardware_ARITHMETICANDLOGICSTRUCTURES ,Quantum Physics (quant-ph) - Abstract
A quantum state transformation can be generally approximated by single- and two-qubit gates. This, however, does not hold with noisy intermediate-scale quantum technologies due to the errors appearing in the gate operations, where errors of two-qubit gates such as controlled-NOT and SWAP operations are dominated. In this work, we present a cost efficient single-copy certification for a realization of a two-qubit gate in the presence of depolarization noise, where it is aimed to identify if the realization is noise-free, or not. It is shown that entangled resources such as entangled states and a joint measurement are not necessary for the purpose, i.e., a noise-free two-qubit gate is not needed to certify an implementation of a two-qubit gate. A proof-of-principle demonstration is presented with photonic qubits., 9 pages. arXiv admin note: text overlap with arXiv:1812.02087
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- 2022
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5. Quantum amplitude amplification operators: exact quantum search
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Hyeokjea Kwon and Joonwoo Bae
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- 2022
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6. A Hybrid Quantum-Classical Approach to Mitigating Measurement Errors in Quantum Algorithms
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Joonwoo Bae and Hyeokjea Kwon
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Noise measurement ,Computer science ,Quantum noise ,Noise (electronics) ,Theoretical Computer Science ,Computational Theory and Mathematics ,Hardware and Architecture ,Qubit ,Measurement uncertainty ,Quantum algorithm ,Quantum ,Algorithm ,Software ,Quantum computer - Abstract
When noisy intermediate scalable quantum (NISQ) devices are applied in information processing, all of the stages through preparation, manipulation, and measurement of multipartite qubit states contain various types of noise that are generally hard to be verified in practice. In this article, we present a scheme to deal with unknown quantum noise and show that it can be used to mitigate errors in measurement readout with NISQ devices. Quantum detector tomography that identifies a type of noise in a measurement can be circumvented. The scheme applies single-qubit operations only, that are with relatively higher precision than measurement readout or two-qubit gates. A classical post-processing is then performed with measurement outcomes. The scheme is implemented in quantum algorithms with NISQ devices: the Bernstein-Vazirani algorithm and a quantum amplitude estimation algorithm in $\mathrm{IBMQ\_yorktown}$ IBMQ _ yorktown and $\mathrm{IBMQ\_essex}$ IBMQ _ essex . The enhancement in the statistics of the measurement outcomes is presented for both of the algorithms with NISQ devices.
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- 2021
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7. Centroid Angle Estimation for Multiple Unresolved Targets Using Frequency Diversity
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Joonwoo Bae, Dongmin Park, and Joohwan Chun
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Estimation ,Monopulse radar ,Computer science ,Centroid ,Algorithm ,Diversity scheme - Published
- 2021
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8. Channel Coding of a Quantum Measurement
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Joonwoo Bae, Filip Wudarski, Chahan M. Kropf, and Spiros Kechrimparis
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Quantum Physics ,Channel code ,LOCC ,Computer Networks and Communications ,Computer science ,Hilbert space ,FOS: Physical sciences ,020206 networking & telecommunications ,02 engineering and technology ,Topology ,symbols.namesake ,Qubit ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,Electrical and Electronic Engineering ,Quantum Physics (quant-ph) ,Quantum information science ,Protocol (object-oriented programming) ,Quantum ,Communication channel ,Quantum computer - Abstract
In this work, we consider the preservation of a measurement for quantum systems interacting with an environment. Namely, a method of preserving an optimal measurement over a channel is devised, what we call channel coding of a quantum measurement in that operations are applied before and after a channel in order to protect a measurement. A protocol that preserves a quantum measurement over an arbitrary channel is shown only with local operations and classical communication without the use of a larger Hilbert space. Therefore, the protocol is readily feasible with present day's technologies. Channel coding of qubit measurements is presented, and it is shown that a measurement can be preserved for an arbitrary channel for both i) pairs of qubit states and ii) ensembles of equally probable states. The protocol of preserving a quantum measurement is demonstrated with IBM quantum computers., 9pages, 3 figures
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- 2020
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9. Quantum vs Noncontextual Semi-Device-Independent Randomness Certification
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Carles Roch i Carceller, Kieran Flatt, Hanwool Lee, Joonwoo Bae, and Jonatan Bohr Brask
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Quantum Physics ,FOS: Physical sciences ,General Physics and Astronomy ,Quantum Physics (quant-ph) - Abstract
We compare the power of quantum and classical physics in terms of randomness certification from devices which are only partially characterised. We study randomness certification based on state discrimination and take noncontextuality as the notion of classicality. A contextual advantage was recently shown to exist for state discrimination. Here, we develop quantum and noncontextual semi-device independent protocols for random-number generation based on maximum-confidence discrimination, which generalises unambiguous and minimum-error state discrimination. We show that, for quantum eavesdropppers, quantum devices can certify more randomness than noncontextual ones whenever none of the input states are unambiguously identified. That is, a quantum-over-classicaladvantage exists., This work is done in parallel with the paper "Contextual advantages and certification for maximum confidence discrimination", by Flatt et al. 6 pages main text, 10 pages of supplemental material, 5 figures
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- 2022
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10. Non-local network coding in interference channels
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Joonwoo Bae, Ji-Young Yun, and Ashutosh Rai
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Quantum Physics ,Quantum network ,business.industry ,Computer science ,FOS: Physical sciences ,General Physics and Astronomy ,Network Communication Protocols ,Quantum entanglement ,Topology ,Interference (wave propagation) ,01 natural sciences ,Channel capacity ,Quantum nonlocality ,Linear network coding ,0103 physical sciences ,Quantum information ,Quantum Physics (quant-ph) ,010306 general physics ,business ,Communications protocol ,Quantum ,Computer Science::Information Theory ,Computer network ,Communication channel - Abstract
In a network, a channel introduces correlations to the parties that aim to establish a communication protocol. In this work, we present a framework of non-local network coding by exploiting a Bell scenario and show the usefulness of non-local and quantum resources in network coding. Two-sender and two-receiver interference channels are considered, for which network coding is characterized by two-input and four-outcome Bell scenarios. It is shown that non-signaling (quantum) correlations lead to strictly higher channel capacities in general than quantum (local) correlations. It is also shown that, however, more non-locality does not necessarily imply a higher channel capacity. The framework can be generally applied to network communication protocols., 11 pages, 3 figures
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- 2021
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11. How many mutually unbiased bases are needed to detect bound entangled states?
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Dariusz Chruscinski, Joonwoo Bae, Beatrix Hiesmayr, Anindita Bera, and Daniel McNulty
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Statistics and Probability ,Quantum Physics ,Modeling and Simulation ,General Physics and Astronomy ,FOS: Physical sciences ,Statistical and Nonlinear Physics ,Quantum Physics (quant-ph) ,Mathematical Physics - Abstract
From a practical perspective it is advantageous to develop methods that verify entanglement in quantum states with as few measurements as possible. In this paper we investigate the minimal number of mutually unbiased bases (MUBs) needed to detect bound entanglement in bipartite $(d\times d)$-dimensional states, i.e. entangled states that are positive under partial transposition. In particular, we show that a class of entanglement witnesses composed of mutually unbiased bases can detect bound entanglement if the number of measurements is greater than $d/2+1$. This is a substantial improvement over other detection methods, requiring significantly fewer resources than either full quantum state tomography or measuring a complete set of $d+1$ MUBs. Our approach is based on a partial characterisation of the (non-)decomposability of entanglement witnesses. We show that non-decomposability is a universal property of MUBs, which holds regardless of the choice of complementary observables, and we find that both the number of measurements and the structure of the witness play an important role in the detection of bound entanglement., Comment: 11 pages, identical to published version
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- 2021
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12. Contextual advantages and certification for maximum confidence discrimination
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Kieran Flatt, Hanwool Lee, Carles Roch I Carceller, Jonatan Bohr Brask, and Joonwoo Bae
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Quantum Physics ,General Engineering ,General Earth and Planetary Sciences ,FOS: Physical sciences ,Quantum Physics (quant-ph) ,General Environmental Science - Abstract
One of the most fundamental results in quantum information theory is that no measurement can perfectly discriminate between nonorthogonal quantum states. In this work, we investigate quantum advantages for discrimination tasks over noncontextual theories by considering a maximum-confidence measurement that unifies different strategies of quantum state discrimination, including minimum-error and unambiguous discrimination. We first show that maximum-confidence discrimination, as well as unambiguous discrimination, contains contextual advantages. We then consider a semi-device-independent scenario of certifying maximum-confidence measurement. The scenario naturally contains undetected events, making it a natural setting to explore maximum-confidence measurements. We show that the certified maximum confidence in quantum theory also contains contextual advantages. Our results establish how the advantages of quantum theory over a classical model may appear in a realistic scenario of a discrimination task.
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- 2021
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13. Measurement protection in prepare-and-measure quantum key distribution
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Joonwoo Bae
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LOCC ,Transmission (telecommunications) ,Computer science ,Quantum state ,business.industry ,Qubit ,Measure (physics) ,Quantum key distribution ,Photonics ,business ,Topology ,Communication channel - Abstract
In the distribution of quantum states over a long distance, not only are quantum states corrupted by interactions with an environment but also a measurement setting should be re-aligned such that detection events can be ensured for the resulting states. We here present a method of protecting a measurement in quantum key distribution against the interactions quantum states experience during the transmission, without the verification of a channel. As a result, a receiver does not have to revise the measurement that has been prepared in a noiseless scenario since it would remain ever optimal. The measurement protection is achieved by applications of local unitary transformations before and after the transmission, that leads to a supermap transforming an arbitrary channel to a depolarization one. An experimental demonstration is presented with the polarization encoding on photonic qubits. It is shown that the security bounds for prepare-and-measure protocols can be improved.
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- 2020
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14. Optimal measurement preserving qubit channels
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Spiros Kechrimparis, Joonwoo Bae, and School of Physical and Mathematical Sciences
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Physics ,Quantum Physics ,Quantum State Discrimination ,General Physics and Astronomy ,FOS: Physical sciences ,Quantum channel ,Topology ,01 natural sciences ,Unitary state ,Quantum Channels ,010305 fluids & plasmas ,Set (abstract data type) ,Computer Science::Emerging Technologies ,Physics [Science] ,Qubit ,0103 physical sciences ,A priori and a posteriori ,010306 general physics ,Quantum Physics (quant-ph) ,Communication channel ,Computer Science::Information Theory - Abstract
We consider the problem of discriminating qubit states that are sent over a quantum channel and derive a necessary and sufficient condition for an optimal measurement to be preserved by the channel. We apply the result to the characterization of optimal measurement preserving (OMP) channels for a given qubit ensemble, e.g., a set of two states or a set of multiple qubit states with equal a priori probabilities. Conversely, we also characterize qubit ensembles for which a given channel is OMP, such as unitary and depolarization channels. Finally, we show how the sets of OMP channels for a given ensemble can be constructed., Comment: 12 pages, 2 figures. Corrected typos
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- 2020
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15. 67-4: Distinguished Paper and Late News-Paper: 5.8-inch QHD Flexible AMOLED Display with Enhanced Bendability of LTPS TFTs
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Jin-Oh Kwag, Hyeyong Chu, Yongsu Lee, Joonwoo Bae, Sung-Hoon Yang, Gyoo-Chul Jo, Jae-Seob Lee, and Thanh Tien Nguyen
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010302 applied physics ,AMOLED ,Materials science ,Strain (chemistry) ,business.industry ,0103 physical sciences ,Optoelectronics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,business ,01 natural sciences - Published
- 2018
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16. 5.8-inch QHD flexible AMOLED display with enhanced bendability of LTPS TFTs
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Yongsu Lee, Joonwoo Bae, Jin-Oh Kwag, Gyoo-Chul Jo, Sung-Hoon Yang, Hyeyong Chu, Jae-Seob Lee, and Thanh Tien Nguyen
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010302 applied physics ,Materials science ,Strain (chemistry) ,business.industry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,AMOLED ,0103 physical sciences ,Optoelectronics ,Electrical and Electronic Engineering ,0210 nano-technology ,business - Published
- 2018
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17. Optimal state discrimination over quantum channels
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Joonwoo Bae
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Physics ,Quantum mechanics ,State (functional analysis) ,Quantum - Published
- 2019
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18. Erratum to 'Channel Coding of a Quantum Measurement'
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Spiros Kechrimparis, Joonwoo Bae, Chahan M. Kropf, and Filip Wudarski
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Channel code ,Computer Networks and Communications ,Computer science ,Electronic engineering ,Quantum measurement ,Electrical and Electronic Engineering - Published
- 2020
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19. Quantifying the nonclassicality of pure dephasing
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Joonwoo Bae, Hong Bin Chen, Ping Yuan Lo, Yueh-Nan Chen, Franco Nori, and Clemens Gneiting
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0301 basic medicine ,Quantum information ,Dephasing ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Quantum mechanics ,General Biochemistry, Genetics and Molecular Biology ,Article ,03 medical and health sciences ,Open quantum system ,symbols.namesake ,Statistical physics ,Qutrit ,lcsh:Science ,Quantum ,Physics ,Quantum Physics ,Multidisciplinary ,General Chemistry ,021001 nanoscience & nanotechnology ,030104 developmental biology ,Quantum process ,Qubit ,symbols ,lcsh:Q ,Quantum Physics (quant-ph) ,0210 nano-technology ,Hamiltonian (quantum mechanics) ,Theoretical physics - Abstract
One of the central problems in quantum theory is to characterize, detect, and quantify quantumness in terms of classical strategies. Dephasing processes, caused by non-dissipative information exchange between quantum systems and environments, provides a natural platform for this purpose, as they control the quantum-to-classical transition. Recently, it has been shown that dephasing dynamics itself can exhibit (non)classical traits, depending on the nature of the system-environment correlations and the related (im)possibility to simulate these dynamics with Hamiltonian ensembles---the classical strategy. Here we establish the framework of detecting and quantifying the nonclassicality for pure dephasing dynamics. The uniqueness of the canonical representation of Hamiltonian ensembles is shown, and a constructive method to determine the latter is presented. We illustrate our method for qubit, qutrit, and qubit-pair pure dephasing and describe how to implement our approach with quantum process tomography experiments. Our work is readily applicable to present-day quantum experiments., 23 pages, 5 figures
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- 2018
20. How useful is a single entanglement witness? (Conference Presentation)
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Joonwoo Bae
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Presentation ,Theoretical computer science ,Computer science ,media_common.quotation_subject ,Quantum Physics ,Construct (python library) ,Quantum entanglement ,Quantum information ,Quantum information processing ,Computer Science::Databases ,Entanglement witness ,media_common - Abstract
Entanglement detection is one of the most fundamental and practical tasks for quantum information processing. The framework of entanglement witnesses provides an experimentally feasible method detecting entangled states. Although It is clear that no entanglement witness per se can detect all entangled states, little is known about how useful a single entanglement witness is. In this work, we show that an entanglement witness can construct another entanglement witness. This means that the same measurement outcomes can be repeatedly applied to constructing different entanglement witnesses.
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- 2018
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21. More Entanglement Implies Higher Performance in Channel Discrimination Tasks
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Marco Piani, Joonwoo Bae, and Dariusz Chruściński
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Degree (graph theory) ,Computer science ,Schmidt number ,Multiplicative function ,General Physics and Astronomy ,Quantum Physics ,Quantum entanglement ,State (functional analysis) ,01 natural sciences ,Task (computing) ,Robustness (computer science) ,0103 physical sciences ,010306 general physics ,Algorithm ,Communication channel - Abstract
We show that every entangled state provides an advantage in ancilla-assisted bi- and multichannel discrimination that singles out its degree of entanglement, quantified in terms of the Schmidt number. The Schmidt-number robustness provides a compelling quantification of such an advantage, and, remarkably, the well-known robustness of entanglement exactly provides the largest multiplicative advantage an entangled state can provide compared to the case where no ancilla is used in a channel discrimination task.
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- 2018
22. Information-Theoretic Meaning of Quantum Information Flow and Its Applications to Amplitude Amplification Algorithms
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Sudipto Singha Roy, Joonwoo Bae, and UAM. Departamento de Física Teórica
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Physics ,Quantum Physics ,Quantum dynamics ,Computation ,Física ,FOS: Physical sciences ,01 natural sciences ,Quantum evolution ,010305 fluids & plasmas ,Amplitude amplification ,0103 physical sciences ,Quantum system ,Quantum algorithm ,Quantum information ,010306 general physics ,Quantum Physics (quant-ph) ,Algorithm ,Quantum - Abstract
The advantages of quantum information processing are in many cases obtained as consequences of quantum interactions, especially for computational tasks where two-qubit interactions are essential. In this work, we establish the framework of analyzing and quantifying loss or gain of information on a quantum system when the system interacts with its environment. We show that the information flow, the theoretical method of characterizing (non-)Markovianity of quantum dynamics, corresponds to the rate of the minimum uncertainty about the system given quantum side information. Thereafter, we analyze the information exchange among subsystems that are under the performance of quantum algorithms, in particular, the amplitude amplification algorithms where the computational process relies fully on quantum evolution. Different realizations of the algorithm are considered, such as i)quantum circuits, ii) analog computation, and iii) adiabatic computation. It is shown that, in all the cases, our formalism provides insights about the process of amplifying the amplitude from the information flow or leakage on the subsystems., Comment: 7 pages, 5 figures, close to the published version
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- 2018
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23. Practical schemes of detecting entanglement with a single Hong-Ou-Mandel interferometer via quantum 2-design
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Joonwoo Bae
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Physics ,Quantum technology ,Interferometry ,Quantum mechanics ,Quantum sensor ,Quantum metrology ,Quantum Physics ,Quantum entanglement ,Quantum tomography ,Quantum information science ,Mach–Zehnder interferometer - Abstract
In this work, we show that measurement in quantum 2-design, such as mutually unbiased bases (MUBs) or symmetric, informationally complete states (SICs), improves the capability of detecting entangled states both theoretically and experimentally. On the theoretical side, we show that measurement in quantum 2-design can detect entangled states twice compared to entanglement witnesses. On the implementation side, we present the scheme of entanglement detection with two detectors only of a Hong-Ou-Mandel interferometer. The experimental scheme applies single-copy level measurement followed by post-processing of measurement outcomes, which is feasible with current technologies.
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- 2017
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24. Improved measurement-device-independent quantum key distribution with uncharacterized qubits
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Joonwoo Bae, Won-Young Hwang, and Hong-Yi Su
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Physics ,Quantum Physics ,Phase (waves) ,FOS: Physical sciences ,Nanotechnology ,Quantum key distribution ,01 natural sciences ,010309 optics ,Measurement device ,Qubit ,0103 physical sciences ,Bit error rate ,Key (cryptography) ,Statistical physics ,Quantum Physics (quant-ph) ,010306 general physics - Abstract
We propose an improved bound for the difference between phase and bit error rate in measurement-device-independent quantum key distribution with uncharacterized qubits. We show by simulations that the bound considerably increases the final key rates., Comment: 4 pages, 3 figures
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- 2017
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25. No-signaling quantum key distribution: solution by linear programming
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Won-Young Hwang, Nathan Killoran, and Joonwoo Bae
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Quantum Physics ,Key generation ,Linear programming ,Computer science ,Generalization ,FOS: Physical sciences ,Statistical and Nonlinear Physics ,Mutual information ,Quantum key distribution ,Theoretical Computer Science ,Electronic, Optical and Magnetic Materials ,Joint probability distribution ,Modeling and Simulation ,Quantum mechanics ,Signal Processing ,Key (cryptography) ,Applied mathematics ,Electrical and Electronic Engineering ,Quantum Physics (quant-ph) ,Computer Science::Cryptography and Security ,Quantum computer - Abstract
We outline a straightforward approach for obtaining a secret key rate using only no-signaling constraints and linear programming. Assuming an individual attack, we consider all possible joint probabilities. Initially, we study only the case where Eve has binary outcomes, and we impose constraints due to the no-signaling principle and given measurement outcomes. Within the remaining space of joint probabilities, by using linear programming, we get bound on the probability of Eve correctly guessing Bob's bit. We then make use of an inequality that relates this guessing probability to the mutual information between Bob and a more general Eve, who is not binary-restricted. Putting our computed bound together with the Csisz\'ar-K\"orner formula, we obtain a positive key generation rate. The optimal value of this rate agrees with known results, but was calculated in a more straightforward way, offering the potential of generalization to different scenarios., Comment: 5 pages, 1 figure, derivation much simplifed
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- 2014
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26. Discrimination of two-qubit unitaries via local operations and classical communication
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Joonwoo Bae
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Discrete mathematics ,LOCC ,Quantum Physics ,Multidisciplinary ,Computer science ,Contrast (statistics) ,FOS: Physical sciences ,Unitary state ,Article ,Qubit ,Mathematical formulation of quantum mechanics ,Bipartite graph ,Quantum information ,Quantum Physics (quant-ph) ,Finite set - Abstract
Distinguishability is a fundamental and operational task generally connected to information applications. In quantum information theory, from the postulates of quantum mechanics it often has an intrinsic limitation, which then dictates and also characterises capabilities of related information tasks. In this work, we consider discrimination between bipartite two-qubit unitary transformations by local operations and classical communication (LOCC) and its relations to entangling capabilities of given unitaries. We show that a pair of entangling unitaries which do not contain local parts, if they are perfectly distinguishable by global operations, can also be perfectly distinguishable by LOCC. There also exist non-entangling unitaries, e.g. local unitaries, that are perfectly discriminated by global operations but not by LOCC. The results show that capabilities of LOCC are strictly restricted than global operations in distinguishing bipartite unitaries for a finite number of repetitions, contrast to discrimination of a pair of bipartite states and also to asymptotic discrimination of unitaries., 9pages, 3 figures
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- 2015
27. Three-party quantum teleportation with asymmetric states
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Y. Kwon, Jitae Kim, Joonwoo Bae, Jyoungwan Jin, and Chihoon Yoon
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Physics ,Quantum network ,General Mathematics ,Applied Mathematics ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Quantum Physics ,Quantum channel ,Quantum energy teleportation ,Teleportation ,Computer Science::Emerging Technologies ,Superdense coding ,Quantum state ,Quantum mechanics ,No-teleportation theorem ,Quantum teleportation ,Computer Science::Cryptography and Security - Abstract
In this paper, we consider the three-party quantum teleportation using non-symmetric states. Considering all possible teleportation scenarios in the three-party quantum teleportation, we show that the asymmetric teleportation would carry more information than symmetrical ones. We also discuss the relation between teleportation protocols and quantum states classficition.
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- 2005
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28. [Untitled]
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Younghun Kwon and Joonwoo Bae
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Speedup ,Physics and Astronomy (miscellaneous) ,General Mathematics ,TheoryofComputation_GENERAL ,Quantum entanglement ,Quantum search ,Quantum evolution ,Running time ,symbols.namesake ,Theoretical physics ,Quadratic equation ,symbols ,Hamiltonian (quantum mechanics) ,Quantum ,Mathematics - Abstract
We consider the running time of the generalized quantum search Hamiltonian. We provide the surprising result that the maximum speedup of quantum search in the generalized Hamiltonian is an O(1) running time regardless of the number of total states. This seems to violate the proof of Zalka that the quadratic speedup is optimal in quantum search. However the argument of Giovannetti et al. that a quantum speedup comes from the interaction between subsystems (or, equivalently entanglement) (and is concerned with the Margolus and Levitin theorem) supports our result.
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- 2003
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29. [Untitled]
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Joonwoo Bae and Younghun Kwon
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Physics ,symbols.namesake ,Quantum decoherence ,Physics and Astronomy (miscellaneous) ,General Mathematics ,Quantum mechanics ,symbols ,Perturbation (astronomy) ,Quantum algorithm ,Hamiltonian (quantum mechanics) ,Computer Science::Databases ,Quantum search ,Running time - Abstract
In general, a quantum algorithm wants to avoid decoherence or perturbation, since such factors may cause errors in the algorithm. We show that some perturbations to the generalized quantum search Hamiltonian can reduce the running time and enhance the success probability. We also provide the narrow bound to the perturbation which can be beneficial to quantum search. In addition, we show that the error induced by a perturbation on the Farhi and Gutmann Hamiltonian can be corrected by another perturbation.
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- 2003
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30. Designing quantum information processing via structural physical approximation
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Joonwoo Bae
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Quantum Physics ,business.industry ,Computer science ,Computation ,Structure (category theory) ,FOS: Physical sciences ,General Physics and Astronomy ,01 natural sciences ,Unitary state ,010305 fluids & plasmas ,Quantum state ,Qubit ,0103 physical sciences ,Statistical physics ,Photonics ,Quantum information ,Quantum Physics (quant-ph) ,010306 general physics ,business ,Quantum - Abstract
In quantum information processing it may be possible to have efficient computation and secure communication beyond the limitations of classical systems. In a fundamental point of view, however, evolution of quantum systems by the laws of quantum mechanics is more restrictive than classical systems, identified to a specific form of dynamics, that is, unitary transformations and, consequently, positive and completely positive maps to subsystems. This also characterizes classes of disallowed transformations on quantum systems, among which positive but not completely maps are of particular interest as they characterize entangled states, a general resource in quantum information processing. Structural physical approximation offers a systematic way of approximating those non-physical maps, positive but not completely positive maps, with quantum channels. Since it has been proposed as a method of detecting entangled states, it has stimulated fundamental problems on classifications of positive maps and the structure of Hermitian operators and quantum states, as well as on quantum measurement such as quantum design in quantum information theory. It has developed efficient and feasible methods of directly detecting entangled states in practice, for which proof-of-principle experimental demonstrations have also been performed with photonic qubit states. Here, we present a comprehensive review on quantum information processing with structural physical approximations and the related progress. The review mainly focuses on properties of structural physical approximations and their applications toward practical information applications., Comment: 53 pages, To appear in Reports on Progress in Physics as a review on structural physical approximation, see also related one, F. Shultz F Journal of Mathematical Physics 57 015218 (2016)
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- 2017
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31. Distilling entanglement with noisy operations
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Younghun Kwon, Joonwoo Bae, and Jinho Chang
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Quantum Physics ,Theoretical computer science ,Physics and Astronomy (miscellaneous) ,Computer science ,Noise (signal processing) ,FOS: Physical sciences ,TheoryofComputation_GENERAL ,Word error rate ,Quantum entanglement ,01 natural sciences ,Unitary state ,010305 fluids & plasmas ,law.invention ,Quantum error correction ,law ,0103 physical sciences ,Quantum Physics (quant-ph) ,010306 general physics ,Entanglement distillation ,Quantum ,Distillation ,Computer Science::Cryptography and Security - Abstract
Entanglement distillation is a fundamental task in quantum information processing. It not only extracts entanglement out of corrupted systems but also leads to protecting systems of interest against intervention with environment. In this work, we consider a realistic scenario of entanglement distillation where noisy quantum operations are applied. In particular, the two-way distillation protocol that tolerates the highest error rate is considered. We show that among all types of noise there are only four equivalence classes according to the distillability condition. Since the four classes are connected by local unitary transformations, our results can be used to improve entanglement distillability in practice when entanglement distillation is performed in a realistic setting., Comment: 19 pages
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- 2017
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32. Physical approximation of the partial transpose and its application to entanglement detection
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Hyang-Tag Lim, Yong-Su Kim, Joonwoo Bae, Yoon-Ho Kim, and Young-Sik Ra
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Physics ,Transpose ,Quantum mechanics ,Quantum metrology ,Quantum algorithm ,Quantum Physics ,Quantum channel ,Quantum entanglement ,W state ,Topology ,Amplitude damping channel ,Squashed entanglement ,Quantitative Biology::Genomics - Abstract
We report the first experimental implementation of an approximate partial transpose operation for photonic two-qubit systems. Direct detection of entanglement using the partial transpose operation is also demonstrated without performing quantum state tomography.
- Published
- 2013
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33. Minimum-error discrimination of qubit states: Methods, solutions, and properties
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Joonwoo Bae and Won-Young Hwang
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Set (abstract data type) ,Physics ,Property (philosophy) ,General method ,Quantum state ,Quantum mechanics ,Qubit ,A priori and a posteriori ,Statistical physics ,Quantum information science ,Atomic and Molecular Physics, and Optics - Abstract
We show a geometric formulation for minimum-error discrimination of qubit states that can be applied to arbitrary sets of qubit states given with arbitrary a priori probabilities. In particular, when qubit states are given with equal a priori probabilities, we provide a systematic way of finding optimal discrimination and the complete solution in a closed form. This generally gives a bound to cases when prior probabilities are unequal. Then it is shown that the guessing probability does not depend on detailed relations among the given states, such as the angles between them, but on a property that can be assigned by the set of given states itself. This also shows how a set of quantum states can be modified such that the guessing probability remains the same. Optimal measurements are also characterized accordingly, and a general method of finding them is provided.
- Published
- 2013
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34. Checking the optimality of entanglement witnesses: an application to structural physical approximations
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Maciej Lewenstein, Joonwoo Bae, Jordi Tura, and Remigiusz Augusiak
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Statistics and Probability ,Discrete mathematics ,Quantum Physics ,Conjecture ,General Physics and Astronomy ,FOS: Physical sciences ,Statistical and Nonlinear Physics ,Quantum entanglement ,Separable state ,Modeling and Simulation ,Quantum Physics (quant-ph) ,Mathematical Physics ,Entanglement witness ,Mathematics ,Counterexample - Abstract
In 2008, the conjecture that structural physical approximations to optimal entanglement witnesses are separable states (in general unnormalized) was posed. In an attempt to disprove it, in [K.-C. Ha and S.-H. Kye, Separable states with unique decompositions, arXiv:1210.1088v3], Ha and Kye proposed a decomposable entanglement witness whose SPA is entangled and argued that it is optimal. In this note, which is based on a comment to the latter work [R. Augusiak et al., Comment on "Separable states with unique decompositions", arXiv:1304.2040v1], we show, both analytically and numerically, that this entanglement witness is not optimal, and as such it is not a counterexample to the conjecture. To this end, we make use of a method for checking optimality of entanglement witnesses developed already in [M. Lewenstein et al., Phys. Rev. A 62, 052310 (2000)], however, hardly exploited so far in the literature., Comment: 10 pages, one figure, paper based on the comment arXiv:1304.2040v1
- Published
- 2013
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35. Optimal approximate transpose map via quantum designs and its applications to entanglement detection
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Joonwoo Bae and Amir Kalev
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Physics ,Quantum Physics ,Structure (category theory) ,FOS: Physical sciences ,State (functional analysis) ,Quantum entanglement ,Topology ,Atomic and Molecular Physics, and Optics ,Multipartite ,Quantum state ,Transpose ,Quantum Physics (quant-ph) ,Quantum ,Peres–Horodecki criterion - Abstract
We show that quantum designs characterize the general structure of the optimal approximation of the transpose map on quantum states. Based on this characterization, we propose an implementation of the approximate transpose map by a measurement-and-preparation scheme. The results show that state-manipulation in quantum two-designs suffices for transpose-based quantu3 information applications. In particular, we present how these results can be applied to the framework of detecting multipartite entangled states, for instance, when local measurements or interferometry-based experimental approaches are applied., Comment: 5 pages, 3 figures
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- 2013
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36. Speedup in Quantum Adiabatic Evolution Algorithm
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Joonwoo Bae and Younghun Kwon
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Physics ,Quantum Physics ,Speedup ,Band gap ,FOS: Physical sciences ,General Physics and Astronomy ,Running time ,Adiabatic theorem ,Ground level ,symbols.namesake ,symbols ,Physical and Theoretical Chemistry ,Quantum Physics (quant-ph) ,Adiabatic process ,Hamiltonian (quantum mechanics) ,Algorithm ,Quantum ,Mathematical Physics - Abstract
Quantum adiabatic evolution algorithm suggested by Farhi et al. was effective in solving instances of NP-complete problems. The algorithm is governed by the adiabatic theorem. Therefore, in order to reduce the running time, it is essential to examine the minimum energy gap between the ground level and the next one through the evolution. In this letter, we show a way of speedup in quantum adiabatic evolution algorithm, using the extended Hamiltonian. We present the exact relation between the energy gap and the elements of the extended Hamiltonian, which provides the new point of view to reduce the running time., 5 pages, Latex
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- 2003
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37. Experimental realization of an approximate transpose operation for qutrit systems using a structural physical approximation
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Yong-Su Kim, Joonwoo Bae, Hyang-Tag Lim, Young-Sik Ra, and Yoon-Ho Kim
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Physics ,business.industry ,Quantum Physics ,Quantum entanglement ,Polarization (waves) ,Topology ,Atomic and Molecular Physics, and Optics ,Quantum state ,Transpose ,Quantum system ,Qutrit ,Photonics ,business ,Quantum - Abstract
Although important for detecting entanglement, the transpose operation cannot be directly realized in laboratory because it is a nonphysical operation. It is, however, possible to find an approximate transpose operation using the method known as the structural physical approximation (SPA); recently, SPA-based implementations of the transpose and partial transpose have been demonstrated for a single-qubit [Phys. Rev. A 83, 020301(R) (2011)] and an entangled two-qubit system [Phys. Rev. Lett. 107, 160401 (2011)]. In this work, we expand SPA-transpose to a three-dimensional quantum system: a qutrit. The photonic qutrit state is encoded in the polarization, and path degrees of freedom of a single-photon and the SPA-transpose operation, which is based on measurement and preparation of quantum states, is implemented with linear optics. Our work paves the way toward entanglement detection for higher-dimensional quantum systems.
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- 2012
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38. Experimental realization of an approximate partial transpose for photonic two-qubit systems
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Young-Sik Ra, Yong-Su Kim, Yoon-Ho Kim, Hyang-Tag Lim, and Joonwoo Bae
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Quantum network ,Quantum discord ,Computer science ,Quantum sensor ,General Physics and Astronomy ,Quantum simulator ,Quantum channel ,Quantum entanglement ,Quantum capacity ,Topology ,Quantum technology ,Open quantum system ,Quantum error correction ,Quantum state ,Quantum mechanics ,Quantum process ,Qubit ,Quantum operation ,Quantum algorithm ,Quantum information ,Amplitude damping channel ,Quantum ,Peres–Horodecki criterion - Abstract
The partial transpose by which a subsystem's quantum state is solely transposed is of unique importance in quantum information processing from both fundamental and practical point of view. In this work, we present a practical scheme to realize a physical approximation to the partial transpose using local measurements on individual quantum systems and classical communication. We then report its linear optical realization and show that the scheme works with no dependence on local basis of given quantum states. A proof-of-principle demonstration of entanglement detection using the physical approximation of the partial transpose is also reported.
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- 2012
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39. Realizing physical approximation of the partial transpose
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Hyang-Tag Lim, Joonwoo Bae, Yoon-Ho Kim, Yong-Su Kim, and Young-Sik Ra
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Computer science ,FOS: Physical sciences ,Quantum simulator ,Quantum capacity ,Quantum channel ,Quantum entanglement ,Quantum imaging ,Topology ,Open quantum system ,Quantum state ,Quantum error correction ,Quantum mechanics ,Transpose ,Quantum operation ,Quantum metrology ,Quantum phase estimation algorithm ,Quantum information ,Amplitude damping channel ,Quantum ,Quantum computer ,Quantum Physics ,Quantum network ,Quantum discord ,Quantum sensor ,Quantum technology ,Quantum process ,Quantum algorithm ,Quantum Physics (quant-ph) - Abstract
The partial transpose by which a subsystem's quantum state is solely transposed is of unique importance in quantum information processing from both fundamental and practical point of view. In this work, we present a practical scheme to realize a physical approximation to the partial transpose using local measurements on individual quantum systems and classical communication. We then report its linear optical realization and show that the scheme works with no dependence on local basis of given quantum states. A proof-of-principle demonstration of entanglement detection using the physical approximation of the partial transpose is also reported., Comment: 5 pages with appendix, 3 figures
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- 2012
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40. Experimental Implementation of an Approximate Partial Transpose for Two-Qubit Systems
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Joonwoo Bae, Yong-Su Kim, Young-Sik Ra, Hyang-Tag Lim, and Yoon-Ho Kim
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Physics ,Qubit ,Transpose ,Quantum mechanics ,Quantum algorithm ,Quantum Physics ,Quantum entanglement ,Quantum channel ,Topology ,Squashed entanglement ,Quantitative Biology::Genomics ,Realization (systems) ,Quantum teleportation - Abstract
We report the first experimental realization of an approximate partial transpose for photonic two-qubit systems. Direct detection of entanglement, i.e., without performing quantum state tomography, using the partial transpose operation, is also demonstrated.
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- 2012
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41. Structure of minimum-error quantum state discrimination
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Joonwoo Bae
- Subjects
Quantum Physics ,Bloch sphere ,Structure (category theory) ,Information processing ,General Physics and Astronomy ,FOS: Physical sciences ,State (functional analysis) ,Set (abstract data type) ,Quantum state ,Qubit ,Statistical physics ,Quantum Physics (quant-ph) ,Equivalence class ,Mathematics - Abstract
Distinguishing different quantum states is a fundamental task having practical applications for information processing. Despite the efforts devoted so far, however, strategies for optimal discrimination are known only for specific examples. We here consider the problem of minimum-error quantum state discrimination where the average error is attempted to be minimized. We show the general structure of minimum-error state discrimination as well as useful properties to derive analytic solutions. Based on the general structure, we present a geometric formulation of the problem, which can be applied to cases where quantum state geometry is clear. We also introduce equivalent classes of sets of quantum states in terms of minimum-error discrimination: sets of quantum states in an equivalence class share the same guessing probability. In particular, for qubit states where the state geometry is found with the Bloch sphere, we illustrate that for an arbitrary set of qubit states, the minimum-error state discrimination with equal prior probabilities can be analytically solved, that is, optimal measurement and the guessing probability are explicitly obtained., Comment: 35 pages
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- 2012
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42. Physical implementation of non-physical quantum operations: realization of the universal transpose operation
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Young-Sik Ra, Yoon-Ho Kim, Joonwoo Bae, Hyang-Tag Lim, and Yong-Su Kim
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Quantum network ,Computer science ,Quantum sensor ,Quantum simulator ,Quantum capacity ,Quantum channel ,Topology ,Open quantum system ,Quantum state ,Quantum error correction ,Qubit ,Quantum process ,Quantum mechanics ,Quantum operation ,Quantum algorithm ,Quantum information ,Quantum ,Quantum computer - Abstract
The universal transpose of quantum states is an anti-unitary transformation that is not allowed in quantum theory. In this work, we investigate approximating the universal transpose of quantum states of two-level systems (qubits) using the method known as structural physical approximation. We also report its experimental implementation in linear optics. The scheme is optimal in that the maximal fidelity is attained, and also practical as measurement and preparation of quantum states that are experimentally feasible within current technologies are solely applied.
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- 2011
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43. No-signaling principle can determine optimal quantum state discrimination
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Won-Young Hwang, Joonwoo Bae, and Yeong-Deok Han
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Quantum Physics ,FOS: Physical sciences ,General Physics and Astronomy ,Quantum capacity ,POVM ,Quantum probability ,Probability amplitude ,Quantum state ,Quantum mechanics ,Quantum process ,Quantum operation ,Applied mathematics ,Quantum algorithm ,Quantum Physics (quant-ph) ,Mathematics - Abstract
We provide a general framework of utilizing the no-signaling principle in derivation of the guessing probability in the minimum-error quantum state discrimination. We show that, remarkably, the guessing probability can be determined by the no-signaling principle. This is shown by proving that in the semidefinite programming for the discrimination, the optimality condition corresponds to the constraint that quantum theory cannot be used for a superluminal communication. Finally, a general bound to the guessing probability is presented in a closed form., 4 pages
- Published
- 2011
44. Experimental implementation of the universal transpose operation using the structural physical approximation
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Hyang-Tag Lim, Joonwoo Bae, Yoon-Ho Kim, Yong-Su Kim, and Young-Sik Ra
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Physics ,Work (thermodynamics) ,Transformation (function) ,Current (mathematics) ,Quantum state ,Transpose ,media_common.quotation_subject ,Qubit ,Antiunitary operator ,Fidelity ,Topology ,Atomic and Molecular Physics, and Optics ,media_common - Abstract
The universal transpose of quantum states is an antiunitary transformation that is not allowed in quantum theory. In this work, we investigate approximating the universal transpose of quantum states of two-level systems (qubits) using the method known as the structural physical approximation to positive maps. We also report its experimental implementation in linear optics. The scheme is optimal in that the maximal fidelity is attained and also practical as measurement and preparation of quantum states that are experimentally feasible within current technologies are solely applied.
- Published
- 2011
- Full Text
- View/download PDF
45. Experimental implementation of the universal transpose operation using structural physical approximation
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Yong-Su Kim, Young-Sik Ra, Joonwoo Bae, Yoon-Ho Kim, and Hyang-Tag Lim
- Subjects
Quantum optics ,Physics ,Classical mechanics ,Spontaneous parametric down-conversion ,Quantum state ,Qubit ,Transpose ,Applied mathematics ,Quantum entanglement ,Quantum information ,Quantum computer - Abstract
We investigate approximating the universal transpose of quantum states of two-level systems (qubits) using the method known as the structural physical approximation to positive maps. We also report its experimental implementation in linear optics.
- Published
- 2011
- Full Text
- View/download PDF
46. Optimal quantum state estimation with use of the no-signaling principle
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Xiang-Bin Wang, Won-Young Hwang, Yeong-Deok Han, and Joonwoo Bae
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Physics ,Quantum Physics ,FOS: Physical sciences ,Quantum capacity ,Atomic and Molecular Physics, and Optics ,Open quantum system ,Theoretical physics ,Quantum error correction ,Qubit ,Quantum operation ,Quantum phase estimation algorithm ,Quantum algorithm ,Quantum information ,Quantum Physics (quant-ph) ,Algorithm - Abstract
A simple derivation of the optimal state estimation of a quantum bit was obtained by using the no-signaling principle. In particular, the no-signaling principle determines a unique form of the guessing probability independently of figures of merit, such as the fidelity or information gain. This proves that the optimal estimation for a quantum bit can be achieved by the same measurement for almost all figures of merit., 3 pages, 1 figure
- Published
- 2010
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47. On structural physical approximations and entanglement breaking maps
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Maciej Lewenstein, Remigiusz Augusiak, Joonwoo Bae, and Łukasz Czekaj
- Subjects
Statistics and Probability ,Discrete mathematics ,Quantum Physics ,Conjecture ,Existential quantification ,General Physics and Astronomy ,FOS: Physical sciences ,Statistical and Nonlinear Physics ,Quantum entanglement ,01 natural sciences ,010305 fluids & plasmas ,Set (abstract data type) ,Separable state ,Simple (abstract algebra) ,Modeling and Simulation ,0103 physical sciences ,Transposition (logic) ,010306 general physics ,Quantum Physics (quant-ph) ,Mathematical Physics ,Mathematics ,Communication channel - Abstract
Very recently a conjecture saying that the so-called structural physical approximations (SPAa) to optimal positive maps (optimal entanglement witnesses) give entanglement breaking (EB) maps (separable states) has been posed [J. K. Korbicz {\it et al.}, Phys. Rev. A {\bf 78}, 062105 (2008)]. The main purpose of this contribution is to explore this subject. First, we extend the set of entanglement witnesses (EWs) supporting the conjecture. Then, we ask if SPAs constructed from other than the depolarizing channel maps also lead to EB maps and show that in general this is not the case. On the other hand, we prove an interesting fact that for any positive map $\Lambda$ there exists an EB channel $\Phi$ such that the SPA of $\Lambda$ constructed with the aid of $\Phi$ is again an EB channel. Finally, we ask similar questions in the case of continuous variable systems. We provide a simple way of construction of SPA and prove that in the case of the transposition map it gives EB channel., Comment: 22 pages, improved version, accepted by Journal of Physics A
- Published
- 2010
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48. Superactivation, unlockability, and secrecy distribution of bound information
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Giuseppe Prettico and Joonwoo Bae
- Subjects
Discrete mathematics ,Physics ,Quantum Physics ,FOS: Physical sciences ,Coherent information ,Quantum capacity ,Squashed entanglement ,Atomic and Molecular Physics, and Optics ,Multipartite ,Quantum cryptography ,Quantum mechanics ,Secrecy ,W state ,Quantum Physics (quant-ph) ,Quantum teleportation ,Computer Science::Databases ,Computer Science::Cryptography and Security - Abstract
Bound information, a cryptographic classical analogue of bound entanglement, is defined as classical secret correlations from which no secret key can be extracted. Its existence was conjectured and shown in a multipartite case. In this work, we provide a new example of bound information in a four-partite scenario. Later, using this example, we prove that bound information can be superactivated in a finite-copy scenario and unlockable. We also show that bound entangled states (bound information) can be used to distribute multipartite pure-state entanglement (secret key)., Comment: 7 pages, 2 figures
- Published
- 2010
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49. Experimental Implementation of the Universal Transpose Operation
- Author
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Yoon-Ho Kim, Joonwoo Bae, Yong-Su Kim, Hyang-Tag Lim, and Young-Sik Ra
- Subjects
Quantum Physics ,business.industry ,Computer science ,FOS: Physical sciences ,Quantum channel ,Topology ,Transformation (function) ,Quantum state ,Quantum mechanics ,Quantum process ,Transpose ,Qubit ,Photonics ,Quantum information ,business ,Quantum Physics (quant-ph) - Abstract
The universal transpose of quantum states is an anti-unitary transformation that is not allowed in quantum theory. In this work, we investigate approximating the universal transpose of quantum states of two-level systems (qubits) using the method known as the structural physical approximation to positive maps. We also report its experimental implementation in linear optics. The scheme is optimal in that the maximal fidelity is attained and also practical as measurement and preparation of quantum states that are experimentally feasible within current technologies are solely applied., Comment: 4 pages, 4 figures
- Published
- 2010
- Full Text
- View/download PDF
50. Detection and typicality of bound entangled states
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Simeon Sauer, Joonwoo Bae, Fernando de Melo, Florian Mintert, Beatrix C. Hiesmayr, Andreas Buchleitner, and Markus Tiersch
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Physics ,Quantum Physics ,TheoryofComputation_GENERAL ,FOS: Physical sciences ,Concurrence ,Quantum entanglement ,Upper and lower bounds ,Multipartite entanglement ,Atomic and Molecular Physics, and Optics ,Combinatorics ,Quantum state ,Quantum mechanics ,Bipartite graph ,W state ,Quantum Physics (quant-ph) ,Peres–Horodecki criterion - Abstract
We derive an explicit analytic estimate for the entanglement of a large class of bipartite quantum states which extends into bound entanglement regions. This is done by using an efficiently computable concurrence lower bound, which is further employed to numerically construct a volume of $3 \times 3$ bound entangled states., Comment: 5 pages, 4 figures. Published version
- Published
- 2009
- Full Text
- View/download PDF
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