The Experts below are selected from a list of 95307 Experts worldwide ranked by ideXlab platform
Thomas Vidick - One of the best experts on this subject based on the ideXlab platform.
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self testing of a single Quantum Device under computational assumptions
Conference on Innovations in Theoretical Computer Science, 2021Co-Authors: Tony Metger, Thomas VidickAbstract:Self-testing is a method to characterise an arbitrary Quantum system based only on its classical input-output correlations, and plays an important role in Device-independent Quantum information processing as well as Quantum complexity theory. Prior works on self-testing require the assumption that the system’s state is shared among multiple parties that only perform local measurements and cannot communicate. Here, we replace the setting of multiple non-communicating parties, which is difficult to enforce in practice, by a single computationally bounded party. Specifically, we construct a protocol that allows a classical verifier to robustly certify that a single computationally bounded Quantum Device must have prepared a Bell pair and performed single-qubit measurements on it, up to a change of basis applied to both the Device’s state and measurements. This means that under computational assumptions, the verifier is able to certify the presence of entanglement, a property usually closely associated with two separated subsystems, inside a single Quantum Device. To achieve this, we build on techniques first introduced by Brakerski et al. (2018) and Mahadev (2018) which allow a classical verifier to constrain the actions of a Quantum Device assuming the Device does not break post-Quantum cryptography.
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self testing of a single Quantum Device under computational assumptions
arXiv: Quantum Physics, 2020Co-Authors: Tony Metger, Thomas VidickAbstract:Self-testing is a method to characterise an arbitrary Quantum system based only on its classical input-output correlations. This usually requires the assumption that the system's state is shared among multiple parties that only perform local measurements and cannot communicate. Here, we replace the setting of multiple non-communicating parties, which is difficult to enforce in practice, by a single computationally bounded party. Specifically, we construct a protocol that allows a classical verifier to robustly certify that a single computationally bounded Quantum Device must have prepared a Bell pair and performed single-qubit measurements on it, up to a change of basis applied to both the Device's state and measurements. This means that under computational assumptions, the verifier is able to certify the presence of entanglement inside a single Quantum Device. We achieve this using techniques introduced by Brakerski et al. (2018) and Mahadev (2018) which allow a classical verifier to constrain the actions of a Quantum Device assuming the Device does not break post-Quantum cryptography.
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a cryptographic test of Quantumness and certifiable randomness from a single Quantum Device
Foundations of Computer Science, 2018Co-Authors: Zvika Brakerski, Paul Christiano, Urmila Mahadev, Umesh Vazirani, Thomas VidickAbstract:We give a protocol for producing certifiable randomness from a single untrusted Quantum Device that is polynomial-time bounded. The randomness is certified to be statistically close to uniform from the point of view of any computationally unbounded Quantum adversary, that may share entanglement with the Quantum Device. The protocol relies on the existence of post-Quantum secure trapdoor claw-free functions, and introduces a new primitive for constraining the power of an untrusted Quantum Device. We then show how to construct this primitive based on the hardness of the learning with errors (LWE) problem. The randomness protocol can also be used as the basis for an efficiently verifiable "Quantum supremacy" proposal, thus answering an outstanding challenge in the field.
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a cryptographic test of Quantumness and certifiable randomness from a single Quantum Device
arXiv: Quantum Physics, 2018Co-Authors: Zvika Brakerski, Paul Christiano, Urmila Mahadev, Umesh Vazirani, Thomas VidickAbstract:We give a protocol for producing certifiable randomness from a single untrusted Quantum Device that is polynomial-time bounded. The randomness is certified to be statistically close to uniform from the point of view of any computationally unbounded Quantum adversary, that may share entanglement with the Quantum Device. The protocol relies on the existence of post-Quantum secure trapdoor claw-free functions, and introduces a new primitive for constraining the power of an untrusted Quantum Device. We show how to construct this primitive based on the hardness of the learning with errors (LWE) problem, and prove that it has a crucial adaptive hardcore bit property. The randomness protocol can be used as the basis for an efficiently verifiable "test of Quantumness", thus answering an outstanding challenge in the field.
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certifiable randomness from a single Quantum Device
2018Co-Authors: Zvika Brakerski, Paul Christiano, Urmila Mahadev, Umesh Vazirani, Thomas VidickAbstract:We give a protocol for producing certifiable randomness from a single untrusted Quantum Device that is polynomial-time bounded. The randomness is certified to be statistically close to uniform from the point of view of any computationally unbounded Quantum adversary, that may share entanglement with the Quantum Device. The protocol relies on the existence of post-Quantum secure trapdoor claw-free functions, and introduces a new primitive for constraining the power of an untrusted Quantum Device. We then show how to construct this primitive based on the hardness of the learning with errors (LWE) problem. The randomness protocol can also be used as the basis for an efficiently verifiable Quantum supremacy proposal, thus answering an outstanding challenge in the field.
Luca Banszerus - One of the best experts on this subject based on the ideXlab platform.
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dispersive sensing of charge states in a bilayer graphene Quantum dot
Applied Physics Letters, 2021Co-Authors: Luca Banszerus, Samuel Moller, Eike Icking, Corinne Steiner, Daniel Neumaier, Martin Otto, Kenji WatanabeAbstract:We demonstrate dispersive readout of individual charge states in a gate-defined few-electron Quantum dot in bilayer graphene. We employ a radio frequency reflectometry circuit, where an LC resonator with a resonance frequency close to 280 MHz is directly coupled to an Ohmic contact of the Quantum dot Device. The detection scheme based on changes in the Quantum capacitance operates over a wide gate-voltage range and allows us to probe excited states down to the single-electron regime. Crucially, the presented sensing technique avoids the use of an additional, capacitively coupled Quantum Device such as a Quantum point contact or single electron transistor, making dispersive sensing particularly interesting for gate-defined graphene Quantum dots.
Andreas Buchleitner - One of the best experts on this subject based on the ideXlab platform.
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Experimental statistical signature of many-body Quantum interference
Nature Photonics, 2018Co-Authors: Taira Giordani, Matteo Pompili, Niko Viggianiello, Mattia Walschaers, Nicolo Spagnolo, Fulvio Flamini, Nathan Wiebe, Andrea Crespi, Roberto Osellame, Andreas BuchleitnerAbstract:Multi-particle interference is an essential ingredient for fundamental Quantum mechanics phenomena and for Quantum information processing to provide a computational advantage, as recently emphasized by boson sampling experiments. Hence, developing a reliable and efficient technique to witness its presence is pivotal in achieving the practical implementation of Quantum technologies. Here, we experimentally identify genuine many-body Quantum interference via a recent efficient protocol, which exploits statistical signatures at the output of a multimode Quantum Device. We successfully apply the test to validate three-photon experiments in an integrated photonic circuit, providing an extensive analysis on the resources required to perform it. Moreover, drawing upon established techniques of machine learning, we show how such tools help to identify the—a priori unknown—optimal features to witness these signatures. Our results provide evidence on the efficacy and feasibility of the method, paving the way for its adoption in large-scale implementations.An experimental protocol to discern true multi-particle interference is demonstrated in a boson sampling Device without dynamic reconfiguration. Statistical features of three-photon interference were evaluated in a seven-mode integrated interferometer.
Kenji Watanabe - One of the best experts on this subject based on the ideXlab platform.
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dispersive sensing of charge states in a bilayer graphene Quantum dot
Applied Physics Letters, 2021Co-Authors: Luca Banszerus, Samuel Moller, Eike Icking, Corinne Steiner, Daniel Neumaier, Martin Otto, Kenji WatanabeAbstract:We demonstrate dispersive readout of individual charge states in a gate-defined few-electron Quantum dot in bilayer graphene. We employ a radio frequency reflectometry circuit, where an LC resonator with a resonance frequency close to 280 MHz is directly coupled to an Ohmic contact of the Quantum dot Device. The detection scheme based on changes in the Quantum capacitance operates over a wide gate-voltage range and allows us to probe excited states down to the single-electron regime. Crucially, the presented sensing technique avoids the use of an additional, capacitively coupled Quantum Device such as a Quantum point contact or single electron transistor, making dispersive sensing particularly interesting for gate-defined graphene Quantum dots.
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atomistic defect states as Quantum emitters in monolayer mos _2
arXiv: Mesoscale and Nanoscale Physics, 2019Co-Authors: Julian Klein, Kenji Watanabe, Michael Lorke, Matthias Florian, Florian Sigger, Jakob Wierzbowski, J Cerne, Kai Muller, Takashi Taniguchi, Ursula WurstbauerAbstract:Quantum light sources in solid-state systems are of major interest as a basic ingredient for integrated Quantum Device technologies. The ability to tailor Quantum emission through deterministic defect engineering is of growing importance for realizing scalable Quantum architectures. However, a major difficulty is that defects need to be positioned site-selectively within the solid. Here, we overcome this challenge by controllably irradiating single-layer MoS$_{2}$ using a sub-nm focused helium ion beam to deterministically create defects. Subsequent encapsulation of the ion bombarded MoS$_{2}$ flake with high-quality hBN reveals spectrally narrow emission lines that produce photons at optical wavelengths in an energy window of one to two hundred meV below the neutral 2D exciton of MoS$_{2}$. Based on ab-initio calculations we interpret these emission lines as stemming from the recombination of highly localized electron-hole complexes at defect states generated by the helium ion bombardment. Our approach to deterministically write optically active defect states in a single transition metal dichalcogenide layer provides a platform for realizing exotic many-body systems, including coupled single-photon sources and exotic Hubbard systems.
Eli A. Sutter - One of the best experts on this subject based on the ideXlab platform.
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Epitaxial graphene on ruthenium
Nature Materials, 2008Co-Authors: Peter W. Sutter, Jan Ingo Flege, Eli A. SutterAbstract:Graphene has been used to explore the fascinating electronic properties of ideal two-dimensional carbon, and shows great promise for Quantum Device architectures. The primary method for isolating graphene, micromechanical cleavage of graphite, is difficult to scale up for applications. Epitaxial growth is an attractive alternative, but achieving large graphene domains with uniform thickness remains a challenge, and substrate bonding may strongly affect the electronic properties of epitaxial graphene layers. Here, we show that epitaxy on Ru(0001) produces arrays of macroscopic single-crystalline graphene domains in a controlled, layer-by-layer fashion. Whereas the first graphene layer indeed interacts strongly with the metal substrate, the second layer is almost completely detached, shows weak electronic coupling to the metal, and hence retains the inherent electronic structure of graphene. Our findings demonstrate a route towards rational graphene synthesis on transition-metal templates for applications in electronics, sensing or catalysis.
