8 results on '"Oblak, Daniel"'
Search Results
2. Are Brain-Computer Interfaces Feasible with Integrated Photonic Chips?
- Author
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Salari, Vahid, Rodrigues, Serafim, Saglamyurek, Erhan, Simon, Christoph, and Oblak, Daniel
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Quantitative Biology - Neurons and Cognition ,Physics - Biological Physics ,Physics - Medical Physics ,Physics - Optics ,Quantum Physics - Abstract
The present paper examines the viability of a radically novel idea for brain-computer interface (BCI), which could lead to novel technological, experimental and clinical applications. BCIs are computer-based systems that enable either one-way or two-way communication between a living brain and an external machine. BCIs read-out brain signals and transduce them into task commands, which are performed by a machine. In closed-loop, the machine can stimulate the brain with appropriate signals. In recent years, it has been shown that there is some ultraweak light emission from neurons within or close to the visible and near-infrared parts of the optical spectrum. Such ultraweak photon emission (UPE) reflects the cellular (and body) oxidative status, and compelling pieces of evidence are beginning to emerge that UPE may well play an informational role in neuronal functions. In fact, several experiments point to a direct correlation between UPE intensity and neural activity, oxidative reactions, EEG activity, cerebral blood flow, cerebral energy metabolism, and release of glutamate. Here, we propose a novel skull implant BCI that uses UPE. We suggest that a photonic integrated chip installed on the interior surface of the skull may enable a new form of extraction of the relevant features from the UPE signals. In the current technology landscape, photonic technologies advance rapidly and poised to overtake many electrical technologies, due to their unique advantages, such as miniaturization, high speed, low thermal effects, and large integration capacity that allow for high yield, volume manufacturing, and lower cost. For our proposed BCI, we make some major conjectures, which need to be experimentally verified, and hence we discuss the controversial parts, feasibility of technology and limitations, and potential impact of this envisaged technology if successfully implemented in the future., Comment: 17 pages, 7 figures. Submitted to "Frontiers in Neuroscience". Comments are welcome
- Published
- 2021
3. Sample-efficient adaptive calibration of quantum networks using Bayesian optimization
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Cortes, Cristian L., Lefebvre, Pascal, Lauk, Nikolai, Davis, Michael J., Sinclair, Neil, Gray, Stephen K., and Oblak, Daniel
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Quantum Physics ,Physics - Computational Physics ,Physics - Optics - Abstract
Indistinguishable photons are imperative for advanced quantum communication networks. Indistinguishability is difficult to obtain because of environment-induced photon transformations and loss imparted by communication channels, especially in noisy scenarios. Strategies to mitigate these transformations often require hardware or software overhead that is restrictive (e.g. adding noise), infeasible (e.g. on a satellite), or time-consuming for deployed networks. Here we propose and develop resource-efficient Bayesian optimization techniques to rapidly and adaptively calibrate the indistinguishability of individual photons for quantum networks using only information derived from their measurement. To experimentally validate our approach, we demonstrate the optimization of Hong-Ou-Mandel interference between two photons -- a central task in quantum networking -- finding rapid, efficient, and reliable convergence towards maximal photon indistinguishability in the presence of high loss and shot noise. We expect our resource-optimized and experimentally friendly methodology will allow fast and reliable calibration of indistinguishable quanta, a necessary task in distributed quantum computing, communications, and sensing, as well as for fundamental investigations.
- Published
- 2021
4. A long-lived solid-state optical quantum memory for high-rate quantum repeaters
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Askarani, Mohsen Falamarzi, Das, Antariksha, Davidson, Jacob H., Amaral, Gustavo C., Sinclair, Neil, Slater, Joshua A., Marzban, Sara, Thiel, Charles W., Cone, Rufus L., Oblak, Daniel, and Tittel, Wolfgang
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Quantum Physics ,Physics - Applied Physics ,Physics - Optics - Abstract
We argue that long optical storage times are required to establish entanglement at high rates over large distances using memory-based quantum repeaters. Triggered by this conclusion, we investigate the $^3$H$_6$ $\leftrightarrow$ $^3$H$_4$ transition at 795.325 nm of Tm:Y$_3$Ga$_5$O$_{12}$ (Tm:YGG). Most importantly, we show that the optical coherence time can reach 1.1 ms, and, using laser pulses, we demonstrate optical storage based on the atomic frequency comb protocol up to 100 $\mu$s as well as a memory decay time T$_M$ of 13.1 $\mu$s. Possibilities of how to narrow the gap between the measured value of T$_m$ and its maximum of 275 $\mu$s are discussed. In addition, we demonstrate quantum state storage using members of non-classical photon pairs. Our results show the potential of Tm:YGG for creating quantum memories with long optical storage times, and open the path to building extended quantum networks., Comment: 6 pages, 4 figures
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- 2021
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5. Improved Light-Matter Interaction for Storage of Quantum States of Light in a Thulium-Doped Crystal Cavity
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Davidson, Jacob H., Lefebvre, Pascal, Zhang, Jun, Oblak, Daniel, and Tittel, Wolfgang
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Quantum Physics ,Physics - Optics - Abstract
We design and implement an atomic frequency comb quantum memory for 793 nm wavelength photons using a monolithic cavity based on a thulium-doped Y$_3$Al$_5$O$_{12}$ (Tm:YAG) crystal. Approximate impedance matching results in the absorption of approximately $90\%$ of input photons and a memory efficiency of (27.5$\pm$ 2.7)% over a 500 MHz bandwidth. The cavity enhancement leads to a significant improvement over the previous efficiency in Tm-doped crystals using a quantum memory protocol. In turn, this allows us for the first time to store and recall quantum states of light in such a memory. Our results demonstrate progress toward efficient and faithful storage of single photon qubits with large time-bandwidth product and multi-mode capacity for quantum networking.
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- 2020
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6. A telecom-wavelength atomic quantum memory in optical fiber for heralded polarization qubits
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Jin, Jeongwan, Saglamyurek, Erhan, Puigibert, Marcel. li Grimau, Verma, Varun B., Marsili, Francesco, Nam, Sae Woo, Oblak, Daniel, and Tittel, Wolfgang
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Quantum Physics ,Physics - Atomic Physics ,Physics - Optics - Abstract
Photon-based quantum information processing promises new technologies including optical quantum computing, quantum cryptography, and distributed quantum networks. Polarization-encoded photons at telecommunication wavelengths provide a compelling platform for practical realization of these technologies. However, despite important success towards building elementary components compatible with this platform, including sources of entangled photons, efficient single photon detectors, and on-chip quantum circuits, a missing element has been atomic quantum memory that directly allows for reversible mapping of quantum states encoded in the polarization degree of a telecom-wavelength photon. Here we demonstrate the quantum storage and retrieval of polarization states of heralded single-photons at telecom-wavelength by implementing the atomic frequency comb protocol in an ensemble of erbium atoms doped into an optical fiber. Despite remaining limitations in our proof-of-principle demonstration such as small storage efficiency and storage time, our broadband light-matter interface reveals the potential for use in future quantum information processing., Comment: The first two authors contributed equally to this work
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- 2015
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7. Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre
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Saglamyurek, Erhan, Jin, Jeongwan, Verma, Varun B., Shaw, Matthew D., Marsili, Francesco, Nam, Sae Woo, Oblak, Daniel, and Tittel, Wolfgang
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Quantum Physics ,Condensed Matter - Materials Science ,Physics - Atomic Physics ,Physics - Optics - Abstract
The realization of a future quantum Internet requires processing and storing quantum information at local nodes, and interconnecting distant nodes using free-space and fibre-optic links. Quantum memories for light are key elements of such quantum networks. However, to date, neither an atomic quantum memory for non-classical states of light operating at a wavelength compatible with standard telecom fibre infrastructure, nor a fibre-based implementation of a quantum memory has been reported. Here we demonstrate the storage and faithful recall of the state of a 1532 nm wavelength photon, entangled with a 795 nm photon, in an ensemble of cryogenically cooled erbium ions doped into a 20 meter-long silicate fibre using a photon-echo quantum memory protocol. Despite its currently limited efficiency and storage time, our broadband light-matter interface brings fibre-based quantum networks one step closer to reality. Furthermore, it facilitates novel tests of light-matter interaction and collective atomic effects in unconventional materials., Comment: 6 pages, 3 Figures + Supplementary Information. The problem with the order of the references is fixed. appears in Nature Photonics (2015)
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- 2014
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8. Entanglement between more than two hundred macroscopic atomic ensembles in a solid
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Zarkeshian, Parisa, Deshmukh, Chetan, Sinclair, Neil, Goyal, Sandeep, Aguillar, Gabriel, Lefebvre, Pascal, Puigibert, Marcel.li, Verma, V., Marsili, F., Shaw, M., Nam, S., Heshami, Khabat, Oblak, Daniel, Tittel, Wolfgang, and Simon, Christoph
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Photon ,Atomic Physics (physics.atom-ph) ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,Physics::Optics ,Quantum entanglement ,01 natural sciences ,Resonance (particle physics) ,Multipartite entanglement ,General Biochemistry, Genetics and Molecular Biology ,Article ,010305 fluids & plasmas ,Physics - Atomic Physics ,Delocalized electron ,Quantum mechanics ,0103 physical sciences ,Quantum information ,010306 general physics ,lcsh:Science ,Quantum ,Quantum optics ,Physics ,Quantum Physics ,Multidisciplinary ,Mathematics::Combinatorics ,General Chemistry ,lcsh:Q ,Quantum Physics (quant-ph) ,Optics (physics.optics) ,Physics - Optics - Abstract
There are both fundamental and practical motivations for studying whether quantum entanglement can exist in macroscopic systems. However, multiparty entanglement is generally fragile and difficult to quantify. Dicke states are multiparty entangled states where a single excitation is delocalized over many systems. Building on previous work on quantum memories for photons, we create a Dicke state in a solid by storing a single photon in a crystal that contains many large atomic ensembles with distinct resonance frequencies. The photon is re-emitted at a well-defined time due to an interference effect analogous to multi-slit diffraction. We derive a lower bound for the number of entangled ensembles based on the contrast of the interference and the single-photon character of the input, and we experimentally demonstrate entanglement between over two hundred ensembles, each containing a billion atoms. We also illustrate the fact that each individual ensemble contains further entanglement., Multipartite entanglement is of both fundamental and practical interest, but is notoriously difficult to witness and characterise. Here, Zarkeshian et al. demonstrate multipartite entanglement in an atomic frequency comb storing a single photon in a Dicke state spread over a macroscopic ensemble.
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- 2017
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