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The article discusses a study on quantum computing conducted by researchers at Quantinuum and published in the journal Science. It mentions that demonstrated the use of advanced quantum simulation to compute molecular arrangements, indicating a shift from theoretical promise to practical application, particularly in chemistry, with potential implications for drug development and materials science.

To harness the potential of a quantum computer, quantum information must be protected against error by encoding it into a logical state that is suitable for quantum error correction. The Gottesman-KitaevPreskill (GKP) qubit is a promising candidate because the required multiqubit operations are readily available at optical frequency. To date, however, GKP qubits have been demonstrated only at mechanical and microwave frequencies. We realized a GKP state in propagating light at telecommunication wavelength and verified it through homodyne measurements without loss corrections. The generation is based on interference of cat states, followed by homodyne measurements. Our final states exhibit nonclassicality and non-Gaussianity, including the trident shape of faint instances of GKP states. Improvements toward brighter, multipeaked GKP qubits will be the basis for quantum computation with light. [ABSTRACT FROM AUTHOR]

The article discusses Australia's significant investment in PsiQuantum to build a large-scale quantum computing facility in Brisbane, Queensland, focusing on the country's gamble on photon-based quantum computing technology. Topics include the advantages of photon-based qubits over traditional approaches, the challenges and advancements in scaling up this technology, and the potential impact of Australia's investment on its quantum computing ecosystem and workforce development.

Quantum technology promises to revolutionize how we learn about the physical world. An experiment that processes quantum data with a quantum computer could have substantial advantages over conventional experiments in which quantum states are measured and outcomes are processed with a classical computer. We proved that quantum machines could learn from exponentially fewer experiments than the number required by conventional experiments. This exponential advantage is shown for predicting properties of physical systems, performing quantum principal component analysis, and learning about physical dynamics. Furthermore, the quantum resources needed for achieving an exponential advantage are quite modest in some cases. Conducting experiments with 40 superconducting qubits and 1300 quantum gates, we demonstrated that a substantial quantum advantage is possible with todayÕs quantum processors. [ABSTRACT FROM AUTHOR]

The article informs on several science researches. Topics include a study by Zhou et al. on quantum simulation using tunable physi cal systems in which gauge symmetry constraints can be effectively implemented; a study by Tian et al. demonstrating real-space imaging of the most representative forms of hydrated protons; and a study by Park et al., in which he developed inactivated whole virus vaccine for influenza A virus.

Quantum walks are the quantum mechanical analog of classical random walks and an extremely powerful tool in quantum simulations, quantum search algorithms, and even for universal quantum computing. In our work, we have designed and fabricated an 8-by-8 two-dimensional square superconducting qubit array composed of 62 functional qubits. We used this device to demonstrate high-fidelity single- and two-particle quantum walks. Furthermore, with the high programmability of the quantum processor, we implemented a Mach-Zehnder interferometer where the quantum walker coherently traverses in two paths before interfering and exiting. By tuning the disorders on the evolution paths, we observed interference fringes with single and double walkers. Our work is a milestone in the field, bringing future larger-scale quantum applications closer to realization for noisy intermediate-scale quantum processors. [ABSTRACT FROM AUTHOR]

The article offers information on challenges for developers of quantum computer to controlling the noise that impacted the intertwined quantum bits. Topics discussed include information on quantum computer from Google which marked the dawn of the age of quantum computing; information on encryption systems which secure internet communications; and use of qubits which made of tiny resonating circuits of superconducting metal etched into microchips.

The article focuses on a new quantum algorithm proposed by computer scientist Oded Regev, which could potentially be more efficient than Peter Shor's 30-year-old algorithm for factoring large numbers, a critical task for hacking internet encryption. Topics discussed include the multidimensional nature of Regev's algorithm, its potential to reduce the number of gates required, and the drawbacks associated with increased memory requirements, which raise questions about its practicality.

The article discusses the potential of negative-temperature heat engines in engine design to demonstrate the creation of a negative-temperature system using interacting photons in a nonlinear optical system. It mentions that the engines contributes to an expanding landscape of thermal possibilities for device design, which includes magnetic spins, cold atoms in optical lattices and quantum computers in thermodynamic exploration that can lead to more-efficient engines.

Large-scale quantum computers will require quantum gate operations between widely separated qubits. A method for implementing such operations, known as quantum gate teleportation (QGT), requires only local operations, classical communication, and shared entanglement. We demonstrate QGT in a scalable architecture by deterministically teleporting a controlled-NOT (CNOT) gate between two qubits in spatially separated locations in an ion trap. The entanglement fidelity of our teleported CNOT is in the interval (0.845, 0.872) at the 95% confidence level. The implementation combines ion shuttling with individually addressed single-qubit rotations and detections, same- and mixed-species two-qubit gates, and real-time conditional operations, thereby demonstrating essential tools for scaling trapped-ion quantum computers combined in a single device. [ABSTRACT FROM AUTHOR]

In the second category, increased computational power could potentially be useful in furthering a field; however, it is unclear whether quantum computing could appreciably accelerate a discovery because of the intrinsic structure of a prob-12 lem's calculations. In his latest book, Quantum Supremacy, theoretical physicist Michio Kaku expertly describes and rectifies common misconceptions about quantum computing - a technology regarded by experts as one that is likely to have profound societal implications. INSIGHTS Quantum Supremacy: How the Quantum Computer Revolution Will Change Everything Michio Kaku Doubleday, 2023. [Extracted from the article]

The article offers information on the Google's quantum supremacy, quantum computer Sycamore and supercomputer. It further discusses that scientists in China have done the computation in a few hours with ordinary processors; supercomputer at Oak Ridge National Laboratory, which has 9216 central processing units and 27,648 faster graphic processing units; and advantage of the tensor network method to do the computations in parallel.

A key step toward demonstrating a quantum system that can address difficult problems in physics and chemistry will be performing a computation beyond the capabilities of any classical computer, thus achieving so-called quantum supremacy. In this study, we used nine superconducting qubits to demonstrate a promising path toward quantum supremacy. By individually tuning the qubit parameters, we were able to generate thousands of distinct Hamiltonian evolutions and probe the output probabilities. The measured probabilities obey a universal distribution, consistent with uniformly sampling the full Hilbert space. As the number of qubits increases, the system continues to explore the exponentially growing number of states. Extending these results to a system of 50 qubits has the potential to address scientific questions that are beyond the capabilities of any classical computer. [ABSTRACT FROM AUTHOR]

Topological superconductors are predicted to host exotic Majorana states that obey non-Abelian statistics and can be used to implement a topological quantum computer. Most of the proposed topological superconductors are realized in difficult-to-fabricate heterostructures at very low temperatures. By using high-resolution spin-resolved and angle-resolved photoelectron spectroscopy, we find that the iron-based superconductor FeTe 1 – x Se x ( x = 0.45; superconducting transition temperature T c = 14.5 kelvin) hosts Dirac-cone – type spin-helical surface states at the Fermi level; the surface states exhibit an s-wave superconducting gap below T c . Our study shows that the surface states of FeTe 0.55 Se 0.45 are topologically superconducting, providing a simple and possibly high-temperature platform for realizing Majorana states. [ABSTRACT FROM AUTHOR]

The article reports that Google's error-correction scheme for quantum computers has been closer to reliability, and Google's engineers aim to reduce the errors that plague quantum computers. It mentions that reducing the errors is possible by spreading the information qubits, marking a significant step toward maintaining qubit's worth of information; and Google's goal of encoding a logical qubit on 1000 physical ones with an error rates requires scaling to be 20 times better.

The article discusses the quantum algorithm for solving the puzzle known as the maximum independent set (MIS) problem using individual atoms trapped in optical tweezers to represent the countries on the map. Topics include demonstration is an important milestone in the broad effort to understand which computational problems stand to benefit from quantum computers; and technological relevance in areas such as supply chain logistics, can be framed as minimizing the cost function.

The article reports that American physicist , Richard Feynman proposed that machines can exploit quantum phenomena to perform otherwise intractable computations. Topics include simulating the properties of a quantum system given its classical description of quantum computer; and near-term quantum computers used as a new type of machine learning device that offers an edge in analyzing data from quantum experiments.

The article reports on ability of quantum computers to crack encryption algorithms used to protect internet communication and mentions federal agencies instructed by administration of president Joe Biden to prepare shift to algorithms resisting quantum attack.

The article presents insights on the increasing popularity of quantum computing. Topics discussed include the efforts of small business enterprises and international businesses to harness quantum mechanics for use in quantum computers, the difference between a classical computer and a quantum computer, and the negative characteristic of quantum superpositions. Also mentioned are the quantum bits or qubits being experimented by companies which include trapped ions and superconducting loops.

The article presents the discussion on Quantum computers (QCs) exponentially speeding up a number of problems in optimization, materials science, and chemistry. Topics include increasing millions of qubits for quantum error correction; background for the solid-state spin qubit provided by creating few-electron quantum dots in 2D electron gas (2DEG) structures; and stating a conducting channel inside the energy gap consisting of a ground state.

The construction of a quantum computer remains a fundamental scientific and technological challenge because of the influence of unavoidable noise. Quantum states and operations can be protected from errors through the use of protocols for quantum computing with faulty components. We present a quantum error-correcting code in which one qubit is encoded in entangled states distributed over seven trapped-ion qubits. The code can detect one bit flip error, one phase flip error, or a combined error of both, regardless on which of the qubits they occur. We applied sequences of gate operations on the encoded qubit to explore its computational capabilities. This seven-qubit code represents a fully functional instance of a topologically encoded qubit, or color code, and opens a route toward fault-tolerant quantum computing. [ABSTRACT FROM AUTHOR]

The article discusses that quantum computers potentially have computational power greater than that of their classical counterparts. It mentions the rapid recent development of superconducting qubits, such as Google's Sycamore quantum processor has enabled quantum supremacy. It also mentions that quantum devices have restricted realizable gates, the ability to compile the circuit for a given architecture is crucial for simulation efficiency and accuracy.

Quantum computation requires controlled engineering of quantum states to perform tasks that go beyond those possible with classical computers. Topological quantum computation aims to achieve this goal by using non-Abelian quantum phases of matter. Such phases allow for quantum information to be stored and manipulated in a nonlocal manner, which protects it from imperfections in the implemented protocols and from interactions with the environment. Recently, substantial progress in this field has been made on both theoretical and experimental fronts. We review the basic concepts of non-Abelian phases and their topologically protected use in quantum information processing tasks. We discuss different possible realizations of these concepts in experimentally available solid-state systems, including systems hosting Majorana fermions, their recently proposed fractional counterparts, and non-Abelian quantum Hall states. [ABSTRACT FROM AUTHOR]

Trapped atomic ions are standards for quantum information processing, serving as quantum memories, hosts of quantum gates in quantum computers and simulators, and nodes of quantum communication networks. Quantum bits based on trapped ions enjoy a rare combination of attributes: They have exquisite coherence properties, they can be prepared and measured with nearly 100% efficiency, and they are readily entangled with each other through the Coulomb interaction or remote photonic interconnects. The outstanding challenge is the scaling of trapped ions to hundreds or thousands of qubits and beyond, at which scale quantum processors can outperform their classical counterparts in certain applications. We review the latest progress and prospects in that effort, with the promise of advanced architectures and new technologies, such as microfabricated ion traps and integrated photonics. [ABSTRACT FROM AUTHOR]

A quantum walk is a time-homogeneous quantum-mechanical process on a graph defined by analogy to classical random walk. The quantum walker is a particle that moves from a given vertex to adjacent vertices in quantum superposition. We consider a generalization to interacting systems with more than one walker, such as the Bose-Hubbard model and systems of fermions or distinguishable particles with nearest-neighbor interactions, and show that multiparticle quantum walk is capable of universal quantum computation. Our construction could, in principle, be used as an architecture for building a scalable quantum computer with no need for time-dependent control. [ABSTRACT FROM AUTHOR]

Although universal quantum computers ideally solve problems such as factoring integers exponentially more efficiently than classical machines, the formidable challenges in building such devices motivate the demonstration of simpler, problem-specific algorithms that still promise a quantum speedup. We constructed a quantum boson-sampling machine (QBSM) to sample the output distribution resulting from the nonclassical interference of photons in an integrated photonic circuit, a problem thought to be exponentially hard to solve classically. Unlike universal quantum computation, boson sampling merely requires indistinguishable photons, linear state evolution, and detectors. We benchmarked our QBSM with three and four photons and analyzed sources of sampling inaccuracy. Scaling up to larger devices could offer the first definitive quantum-enhanced computation. [ABSTRACT FROM AUTHOR]

The article focuses on the Extended Church-Turing thesis which the article suggests would make quantum computers unnecessary for exponentially efficient simulations. It examines the central premise of boson sampling and verifies experimentally three-photon scattering amplitudes are given by submatrice permanents generated from a unitary describing a six-mode integrated optic. It mentions that even with unavoidable effects of imperfect detection, photon loss, and non-ideal sources, the protocol was found to be robust. It suggests that scaling the procedure to a large number of photons would be simpler than constructing a universal quantum computer.

Stable quantum bits, capable both of storing quantum information for macroscopic time scales and of integration inside small portable devices, are an essential building block for an array of potential applications. We demonstrate high-fidelity control of a solid-state qubit, which preserves its polarization for several minutes and features coherence lifetimes exceeding 1 second at room temperature. The qubit consists of a single 13C nuclear spin in the vicinity of a nitrogen-vacancy color center within an isotopically purified diamond crystal. The long qubit memory time was achieved via a technique involving dissipative decoupling of the single nuclear spin from its local environment. The versatility, robustness, and potential scalability of this system may allow for new applications in quantum information science. [ABSTRACT FROM AUTHOR]

A quantum computer requires systems that are isolated from their environment, but can be integrated into devices, and whose states can be measured with high accuracy. Nuclear spins in solids promise long coherence lifetimes, but they are difficult to initialize into known states and to detect with high sensitivity. We show how the distinctive optical properties of enriched 28Si enable the use of hyperfine-resolved optical transitions, as previously applied to great effect for isolated atoms and ions in vacuum. Together with efficient Auger photoionization, these resolved hyperfine transitions permit rapid nuclear hyperpolarization and electrical spin-readout. We combine these techniques to detect nuclear magnetic resonance from dilute 31P in the purest available sample of 28Si, at concentrations inaccessible to conventional measurements, measuring a solid-state coherence time of over 180 seconds. [ABSTRACT FROM AUTHOR]

Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We developed a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic self-interactions (Φ4 theory) in spacetime of four and fewer dimensions. Its run time is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. In the strong-coupling and high-precision regimes, our quantum algorithm achieves exponential speedup over the fastest known classical algorithm. [ABSTRACT FROM AUTHOR]

Quantum computers have the potential to solve certain problems faster than classical computers. To exploit their power, it is necessary to perform interqubit operations and generate entangled states. Spin qubits are a promising candidate for implementing a quantum processor because of their potential for scalability and miniaturization. However, their weak interactions with the environment, which lead to their long coherence times, make interqubit operations challenging. We performed a controlled two-qubit operation between singlet-triplet qubits using a dynamically decoupled sequence that maintains the two-qubit coupling while decoupling each qubit from its fluctuating environment. Using state tomography, we measured the full density matrix of the system and determined the concurrence and the fidelity of the generated state, providing proof of entanglement. [ABSTRACT FROM AUTHOR]

Quantum computers, besides offering substantial computational speedups, are also expected to preserve the privacy of a computation. We present an experimental demonstration of blind quantum computing in which the input, computation, and output all remain unknown to the computer. We exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server. Various blind delegated computations, including one- and two-qubit gates and the Deutsch and Grover quantum algorithms, are demonstrated. The client only needs to be able to prepare and transmit individual photonic qubits. Our demonstration is crucial for unconditionally secure quantum cloud computing and might become a key ingredient for real-life applications, especially when considering the challenges of making powerful quantum computers widely available. [ABSTRACT FROM AUTHOR]

The von Neumann architecture for a classical computer comprises a central processing unit and a memory holding instructions and data. We demonstrate a quantum central processing unit that exchanges data with a quantum random-access memory integrated on a chip, with instructions stored on a classical computer. We test our quantum machine by executing codes that involve seven quantum elements: Two superconducting qubits coupled through a quantum bus, two quantum memories, and two zeroing registers. Two vital algorithms for quantum computing are demonstrated, the quantum Fourier transform, with 66% process fidelity, and the three-qubit Toffoli-class OR phase gate, with 98% phase fidelity. Our results, in combination especially with longer qubit coherence, illustrate a potentially viable approach to factoring numbers and implementing simple quantum error correction codes. [ABSTRACT FROM AUTHOR]

A digital quantum simulator is an envisioned quantum device that can be programmed to efficiently simulate any other local system. We demonstrate and investigate the digital approach to quantum simulation in a system of trapped ions. With sequences of up to 100 gates and 6 qubits, the full time dynamics of a range of spin systems are digitally simulated. Interactions beyond those naturally present in our simulator are accurately reproduced, and quantitative bounds are provided for the overall simulation quality. Our results demonstrate the key principles of digital quantum simulation and provide evidence that the level of control required for a full-scale device is within reach. [ABSTRACT FROM AUTHOR]

Measurement of coupled quantum systems plays a central role in quantum information processing. We have realized independent single-shot read-out of two electron spins in a double quantum dot. The read-out method is all-electrical, cross-talk between the two measurements is negligible, and read-out fidelities are -86% on average. This allows us to directly probe the anticorrelations between two spins prepared in a singlet state and to demonstrate the operation of the two-qubit exchange gate on a complete set of basis states. The results provide a possible route to the realization and efficient characterization of multiqubit quantum circuits based on single quantum dot spins. [ABSTRACT FROM AUTHOR]

Photons are excellent information carriers but normally pass through each other without consequence. Engineered interactions between photons would enable applications as varied as quantum information processing and simulation of condensed matter systems. Using an ensemble of cold atoms strongly coupled to an optical cavity, we found that the transmission of light through a medium may be controlled with few photons and even by the electromagnetic vacuum field. The vacuum induces a group delay of 25 nanoseconds on the input optical pulse, corresponding to a light velocity of 1600 meters per second, and a transparency of 40% that increases to 80% when the cavity is filled with 10 photons. This strongly nonlinear effect provides prospects for advanced quantum devices such as photon number-state filters. [ABSTRACT FROM AUTHOR]

Certain algorithms for quantumcomputers are able to outperform their classical counterparts. In 1994, Peter Shor came up with a quantum algorithm that calculates the prime factors of a large number vastly more efficiently than a classical computer. For general scalability of such algorithms, hardware, quantum error correction, and the algorithmic realization itself need to be extensible. Here we present the realization of a scalable Shor algorithm, as proposed by Kitaev. We factor the number 15 by effectively employing and controlling seven qubits and four "cache qubits" and by implementing generalized arithmetic operations, known as modular multipliers. This algorithm has been realized scalably within an ion-trap quantum computer and returns the correct factors with a confidence level exceeding 99%. [ABSTRACT FROM AUTHOR]

Robust measurement of single quantum bits plays a key role in the realization of quantum computation and communication as well as in quantum metrology and sensing. We have implemented a method for the improved readout of single electronic spin qubits in solid-state systems. The method makes use of quantum logic operations on a system consisting of a single electronic spin and several proximal nuclear spin ancillae in order to repetitively readout the state of the electronic spin. Using coherent manipulation of a single nitrogen vacancy center in room-temperature diamond, full quantum control of an electronic-nuclear system consisting of up to three spins was achieved. We took advantage of a single nuclear-spin memory in order to obtain a 10-fold enhancement in the signal amplitude of the electronic spin readout. We also present a two-level, concatenated procedure to improve the readout by use of a pair of nuclear spin ancillae, an important step toward the realization of robust quantum information processors using electronic- and nuclear-spin qubits. Our technique can be used to improve the sensitivity and speed of spin-based nanoscale diamond magnetometers. [ABSTRACT FROM AUTHOR]

Quantum simulators are controllable quantum systems that can be used to simulate other quantum systems. Being able to tackle problems that are intractable on classical computers, quantum simulators would provide a means of exploring new physical phenomena. We present an overview of how quantum simulators may become a reality in the near future as the required technologies are now within reach. Quantum simulators, relying on the coherent control of neutral atoms, ions, photons, or electrons, would allow studying problems in various fields including condensed-matter physics, high-energy physics, cosmology, atomic physics, and quantum chemistry. [ABSTRACT FROM AUTHOR]

Large-scale quantum information processors must be able to transport and maintain quantum information and repeatedly perform logical operations. Here, we show a combination of all of the fundamental elements required to perform scalable quantum computing through the use of qubits stored in the internal states of trapped atomic ions. We quantified the repeatability of a multiple-qubit operation and observed no loss of performance despite qubit transport over macroscopic distances. Key to these results is the use of different pairs of 9Be+ hypertine states for robust qubit storage, readout, and gates, and simultaneous trapping of 24Mg+ "re-cooling" ions along with the qubit ions. [ABSTRACT FROM AUTHOR]

In quantum information processing, qudits (d-level systems) are an extension of qubits that could speed up certain computing tasks. We demonstrate the operation of a superconducting phase qudit with a number of levels d up to d = 5 and show how to manipulate and measure the qudit state, including simultaneous control of multiple transitions. We used the qudit to emulate the dynamics of single spins with principal quantum number s = ½, 1, and 3/2, allowing a measurement of Berry's phase and the even parity of integer spins (and odd parity of half-integer spins) under 2π-rotation. This extension of the two-level qubit to a multilevel qudit holds promise for more-complex quantum computational architectures and for richer simulations of quantum mechanical systems. [ABSTRACT FROM AUTHOR]

In 2001, all-optical quantum computing became feasible with the discovery that scalable quantum computing is possible using only single-photon sources, linear optical elements, and single-photon detectors. Although it was in principle scalable, the massive resource overhead made the scheme practically daunting. However, several simplifications were followed by proof-of-principle demonstrations, and recent approaches based on cluster states or error encoding have dramatically reduced this worrying resource overhead, making an all-optical architecture a serious contender for the ultimate goal of a large-scale quantum computer. Key challenges will be the realization of high-efficiency sources of indistinguishable single photons, low-loss, scalable optical circuits, high-efficiency single-photon detectors, and low-loss interfacing of these components. [ABSTRACT FROM AUTHOR]

A major goal of developing high-precision control of many-body quantum systems is to realize their potential as quantum computers. A substantial obstacle to this is the extreme fragility of quantum systems to ‘decoherence’ from environmental noise and other control limitations. Although quantum computation is possible if the noise affecting the quantum system satisfies certain conditions, existing methods for noise characterization are intractable for present multibody systems. We introduce a technique based on symmetrization that enables direct experimental measurement of some key properties of the decoherence affecting a quantum system. Our method reduces the number of experiments required from exponential to polynomial in the number of subsystems. The technique is demonstrated for the optimization of control over nuclear spins in the solid state. [ABSTRACT FROM AUTHOR]

The article reports on the announcement by physicists with Google that they have reached a milestone known as quantum supremacy under which Google's 53-qubit processor was able to perform a calculation in 200 seconds that would have taken the world's most powerful supercomputer 10,000 years.

The article reports that the International Business Machines (IBM) cast doubt on a claim by a group at Google that it had used a quantum computer to achieve a computing milestone known as quantum supremacy.

One of the many challenges of building a scalable quantum computeris singleshot measurement of all the quantum bits (qubits). We have usedsimultaneous single-shot measurement of coupled Josephson phase qubitsto directly probe interaction of the qubits in the time domain. Theconcept of measurement crosstalk is introduced, and we show that itseffects are minimized by careful adjustment of the timing of themeasurements. We observe the antiphase oscillation of the two-qubit [ABSTRACT FROM AUTHOR]

Explores the experimental realization of noiseless subsystems for quantum information processing. Security of one bit quantum information against all collective noise in three nuclear spins; Transcription of the quantum bit in a proper noiseless subsystem; Improvement of information storage for a noncommutative set of errors.

Presents a report on Josephson persistent-current qubit. Ability to be fabricated with conventional electron beam lithography and is suited for integration into a large quantum computer; Descriptions; Comments; Outlook.

Presents information that supports the belief that quantum key distribution (QKD) offers unconditional security, or cryptography, in communication between two users. Shows that given fault-tolerant quantum computers, QKD over an arbitrarily long distance of a realistic noisy channel can be made unconditionally secure; How the proof is reduced from a noisy quantum scheme to a noiseless quantum scheme and then to a noiseless classical scheme; The use of classical probability theory.