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Graph adversarial self-supervised learning 21

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Graph adversarial self-supervised learning

Proceedings of the 35th International Conference on Neural Information Processing Systems

作者： Longqi Yang Liangliang Zhang Wenjing Yang Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha China and Defense Innovation Institute Beijing China Institute of Systems Engineering AMS Beijing China Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha China

ISBN: (纸本)9781713845393

This paper studies a long-standing problem of learning the representations of a whole graph without human supervision. The recent self-supervised learning methods train models to be invariant to the transformations (views) of the inputs. However, designing these views requires the experience of human experts. Inspired by adversarial training, we propose an adversarial self-supervised learning (GASSL) framework for learning unsupervised representations of graph data without any handcrafted views. GASSL automatically generates challenging views by adding perturbations to the input and are adversarially trained with respect to the encoder. Our method optimizes the min-max problem and utilizes a gradient accumulation strategy to accelerate the training process. Experimental on ten graph classification datasets show that the proposed approach is superior to state-of-the-art self-supervised learning baselines, which are competitive with supervised models.

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Machine-learning certification of multipartite entanglement for noisy quantum hardware

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arXiv 2024年

作者： Fuchs, Andreas J.C. Brunner, Eric Seong, Jiheon Kwon, Hyeokjea Seo, Seungchan Bae, Joonwoo Buchleitner, Andreas Carnio, Edoardo G. Physikalisches Institut Albert-Ludwigs-Universität Freiburg Hermann-Herder-Straße 3 FreiburgD-79104 Germany Quantinuum Partnership House Carlisle Place LondonSW1P 1BX United Kingdom School of Electrical Engineering Korea Advanced Institute of Science and Technology Daejeon Korea Republic of EUCOR center for Quantum Science and Quantum Computing Albert-Ludwigs-Universität Freiburg Hermann-Herder-Straße 3 FreiburgD-79104 Germany

Entanglement is a fundamental aspect of quantum physics, both conceptually and for its many applications. Classifying an arbitrary multipartite state as entangled or separable—a task referred to as the separability problem—poses a significant challenge, since a state can be entangled with respect to many different of its partitions. We develop a certification pipeline that feeds the statistics of random local measurements into a non-linear dimensionality reduction algorithm, to determine with respect to which partitions a given quantum state is entangled. After training a model on randomly generated quantum states, entangled in different partitions and of varying purity, we verify the accuracy of its predictions on simulated test data, and finally apply it to states prepared on IBM quantum computing hardware. Copyright © 2024, The Authors. All rights reserved.

关键词： quantum entanglement

Fiber-integrated microwave-to-optical quantum transducer

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Physical Review Applied 2023年第4期20卷 044031-044031页

作者： Wenfang Li Jinjin Du C. M. Wilson Michal Bajcsy Institute for Quantum Computing University of Waterloo 200 University Avenue West Waterloo Ontario N2L 3G1 Canada Okinawa Institute of Science and Technology Graduate University Onna Okinawa 904-0495 Japan Department of Electrical and Computer Engineering University of Waterloo 200 University Avenue West Waterloo Ontario N2L 3G1 Canada

We propose an on-chip fiber-based quantum transducer to convert microwave photons into optical-telecommunication-band photons. The device consists of a coplanar-waveguide microwave resonator and a pair of coupled optical cavities integrated into a rare-earth-doped fiber. The microwave resonator is formed by two aluminum strips deposited onto the cladding of the fiber, whose diameter has been etched down to approximately 8μm. We study the conversion process using the cavity electro-optic formalism for a system operating at liquid-helium temperature (around 4 K), as well as using a three-wave mixing approach for operation at millikelvin temperatures achievable in a dilution refrigerator. Both methods predict that unity conversion efficiency could be achievable with realistically achievable experimental parameters. The proposed device acts as a quantum transducer for coherent microwave-to-optical conversion, which has great promise for application in all-fiber integrated quantum devices for quantum information processing.

关键词： Integrated optics Light-matter interaction Optical quantum information processing quantum communication Optical fibers Transducers Microwave techniques Optical techniques

Data centers with quantum random access memory and quantum networks

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arXiv 2022年

作者： Liu, Junyu Hann, Connor T. Jiang, Liang Pritzker School of Molecular Engineering The University of Chicago ChicagoIL60637 United States Kadanoff Center for Theoretical Physics The University of Chicago ChicagoIL60637 United States Chicago Quantum Exchange The University of Chicago ChicagoIL60637 United States Institute for Quantum Information and Matter California Institute of Technology PasadenaCA91125 United States Walter Burke Institute for Theoretical Physics California Institute of Technology PasadenaCA91125 United States AWS Center for Quantum Computing PasadenaCA91125 United States

In this paper, we propose the quantum Data Center (QDC), an architecture combining quantum Random Access Memory (QRAM) and quantum networks. We give a precise definition of QDC, and discuss its possible realizations and extensions. We discuss applications of QDC in quantum computation, quantum communication, and quantum sensing, with a primary focus on QDC for T-gate resources, QDC for multi-party private quantum communication, and QDC for distributed sensing through data compression. We show that QDC will provide efficient, private, and fast services as a future version of data centers. Copyright © 2022, The Authors. All rights reserved.

关键词： quantum communication

Discrete Time Crystal Phase as a Resource for quantum Enhanced Sensing

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arXiv 2024年

作者： Yousefjani, Rozhin Sacha, Krzysztof Bayat, Abolfazl Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610051 China Qatar Center for Quantum Computing College of Science and Engineering Hamad Bin Khalifa University Doha Qatar Instytut Fizyki Teoretycznej Wydzial Fizyki Astronomii i Informatyki Stosowanej Uniwersytet Jagielloński ulica Profesora Stanislawa Lojasiewicza 11 KrakówPL-30-348 Poland Centrum Marka Kaca Uniwersytet Jagielloński ulica Profesora Stanislawa Lojasiewicza 11 KrakówPL-30-348 Poland Key Laboratory of Quantum Physics and Photonic Quantum Information Ministry of Education University of Electronic Science and Technology of China Chengdu611731 China

Discrete time crystals are a special phase of matter in which time translational symmetry is broken through a periodic driving pulse. Here, we first propose and characterize an effective mechanism to generate a stable discrete time crystal phase in a disorder-free many-body system with indefinite persistent oscillations even in finite-size systems. Then we explore the sensing capability of this system to measure the spin exchange coupling. The results show strong quantum-enhanced sensitivity throughout the time crystal phase. As the spin exchange coupling varies, the system goes through a sharp phase transition and enters a non-time crystal phase in which the performance of the probe considerably decreases. We characterize this phase transition as a second-order type and determine its critical properties through a comprehensive finite-size scaling analysis. The performance is independent of the initial states and may even benefit from imperfections in the driving pulse. A simple set of projective measurements can capture the quantum-enhanced sensitivity. © 2024, CC BY.

关键词： Crystal symmetry

Security of device-independent quantum key distribution protocols: a review

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arXiv 2022年

作者： Primaatmaja, Ignatius W. Goh, Koon Tong Tan, Ernest Y.-Z. Khoo, John T.-F. Ghorai, Shouvik Lim, Charles Department of Electrical & Computer Engineering National University of Singapore Singapore Centre for Quantum Technologies National University of Singapore Singapore Institute for Quantum Computing Department of Physics and Astronomy University of Waterloo Canada Department of Computer Science National University of Singapore Singapore Global Technology Applied Research JPMorgan Chase & Co Singapore

Device-independent quantum key distribution (DI-QKD) is often seen as the ultimate key exchange protocol in terms of security, as it can be performed securely with uncharacterised black-box devices. The advent of DI-QKD closes several loopholes and side-channels that plague current QKD systems. While implementing DI-QKD protocols is technically challenging, there have been recent proof-of-principle demonstrations, resulting from the progress made in both theory and experiments. In this review, we will provide an introduction to DI-QKD, an overview of the related experiments performed, and the theory and techniques required to analyse its security. We conclude with an outlook on future DI-QKD research. © 2022, CC BY.

关键词： quantum cryptography

quantum Depth in the Random Oracle Model

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arXiv 2022年

作者： Arora, Atul Singh Coladangelo, Andrea Coudron, Matthew Gheorghiu, Alexandru Singh, Uttam Waldner, Hendrik Institute for Quantum Information and Matter California Institute of Technology Department of Computing and Mathematical Sciences California Institute of Technology United States University of California Berkeley Simons Institute The Theory of Computing United States Department of Computer Science University of Maryland United States Department of Computer Science and Engineering Chalmers University of Technology Institute for Theoretical Studies ETH Zürich Switzerland Center for Theoretical Physics Polish Academy of Sciences Poland Department of Computer Science University of Maryland Max Planck Institute for Security and Privacy United States

We give a comprehensive characterization of the computational power of shallow quantum circuits combined with classical computation. Specifically, for classes of search problems, we show that the following statements hold, relative to a random oracle: (a) BPPQNCBPP ≠ BQP. This refutes Jozsa's conjecture [Joz05] in the random oracle model. As a result, this gives the first instantiatable separation between the classes by replacing the oracle with a cryptographic hash function, yielding a resolution to one of Aaronson's ten semi-grand challenges in quantum computing [Aar05]. (b) BPPQNC ⊆ QNCBPP and QNCBPP ⊆ BPPQNC. This shows that there is a subtle interplay between classical computation and shallow quantum computation. In fact, for the second separation, we establish that, for some problems, the ability to perform adaptive measurements in a single shallow quantum circuit, is more useful than the ability to perform polynomially many shallow quantum circuits without adaptive measurements. (c) There exists a 2-message proof of quantum depth protocol. Such a protocol allows a classical verifier to efficiently certify that a prover must be performing a computation of some minimum quantum depth. Our proof of quantum depth can be instantiated using the recent proof of quantumness construction by Yamakawa and Zhandry [YZ22]. Copyright © 2022, The Authors. All rights reserved.

关键词： Hash functions

quantum Algorithm for Petz Recovery Channels and Pretty Good Measurements

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Physical Review Letters 2022年第22期128卷 220502-220502页

作者： András Gilyén Seth Lloyd Iman Marvian Yihui Quek Mark M. Wilde Institute for Quantum Information and Matter California Institute of Technology Pasadena California 91125 USA Simons Institute for the Theory of Computing Berkeley California 94720 USA Department of Mechanical Engineering and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Physics and Department of Electrical and Computer Engineering Duke University Durham North Carolina 27708 USA Information Systems Laboratory Stanford University Stanford California 94305 USA Hearne Institute for Theoretical Physics Department of Physics and Astronomy and Center for Computation and Technology Louisiana State University Baton Rouge Louisiana 70803 USA Stanford Institute for Theoretical Physics Stanford University Stanford California 94305 USA

The Petz recovery channel plays an important role in quantum information science as an operation that approximately reverses the effect of a quantum channel. The pretty good measurement is a special case of the Petz recovery channel, and it allows for near-optimal state discrimination. A hurdle to the experimental realization of these vaunted theoretical tools is the lack of a systematic and efficient method to implement them. This Letter sets out to rectify this lack: Using the recently developed tools of quantum singular value transformation and oblivious amplitude amplification, we provide a quantum algorithm to implement the Petz recovery channel when given the ability to perform the channel that one wishes to reverse. Moreover, we prove that, in some sense, our quantum algorithm’s usage of the channel implementation cannot be improved by more than a quadratic factor. Our quantum algorithm also provides a procedure to perform pretty good measurements when given multiple copies of the states that one is trying to distinguish.

关键词： quantum algorithms quantum channels quantum error correction

Oscillating photonic Bell state from a semiconductor quantum dot for quantum key distribution

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arXiv 2023年

作者： Pennacchietti, Matteo Cunard, Brady Nahar, Shlok Zeeshan, Mohd Gangopadhyay, Sayan Poole, Philip J. Dalacu, Dan Fognini, Andreas Jöns, Klaus D. Zwiller, Val Jennewein, Thomas Lütkenhaus, Norbert Reimer, Michael E. Institute for Quantum Computing Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada Institute for Quantum Computing Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada National Research Council of Canada OttawaONK1A 0R6 Canada University of Ottawa OttawaONK1N 6N5 Canada Single Quantum B.V. Delft2628 CJ Netherlands Department of Physics Paderborn University Paderborn33098 Germany Department of Applied Physics Royal Institute of Technology Albanova University Centre Stockholm106 91 Sweden

An on-demand source of bright entangled photon pairs is desirable for quantum key distribution (QKD) and quantum repeaters. The leading candidate to generate entangled photon pairs is based on spontaneous parametric down-conversion (SPDC) in a non-linear crystal. However, there exists a fundamental trade-off between entanglement fidelity and efficiency in SPDC sources due to multiphoton emission at high brightness, which limits the pair extraction efficiency to 0.1% when operating at near-unity fidelity. quantum dots in photonic nanostructures can in principle overcome this trade-off;however, the quantum dots that have achieved entanglement fidelities on par with SPDC sources (99%) have poor pair extraction efficiencies of 0.01%. Here, we demonstrate a 65-fold increase in the pair extraction efficiency compared to quantum dots with equivalent peak fidelity from an InAsP quantum dot in a photonic nanowire waveguide. We measure a raw peak concurrence and fidelity of 95.3% ± 0.5% and 97.5% ± 0.8%, respectively. Finally, we show that an oscillating two-photon Bell state generated by a semiconductor quantum dot can be utilized to establish a secure key for QKD, alleviating the need to remove the quantum dot energy splitting of the intermediate exciton states in the biexciton-exciton cascade. © 2023, CC BY.

关键词： Semiconductor quantum dots