The Experts below are selected from a list of 477411 Experts worldwide ranked by ideXlab platform
Stefan Kroll - One of the best experts on this subject based on the ideXlab platform.
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experimental Quantum State tomography of a solid State qubit
Physical Review A, 2008Co-Authors: Lars Rippe, Brian Julsgaard, Andreas Walther, Yan Ying, Stefan KrollAbstract:Quantum-State tomography is used to characterize the State of an ensemble based qubit implemented through two hyperfine levels in Pr3+ ions, doped into a Y2SiO5 crystal. We experimentally verify that single-qubit rotation errors due to inhomogeneities of the ensemble can be suppressed using the Roos-Molmer dark-State scheme [Roos and Molmer, Phys. Rev. A 69, 022321 (2004)] Fidelities above > 90%, presumably limited by excited State decoherence, were achieved. Although not explicitly taken care of in the Roos-Molmer scheme, it appears that also decoherence due to inhomogeneous broadening on the hyperfine transition is largely suppressed.
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complete reconstruction of the Quantum State of a single photon wave packet absorbed by a doppler broadened transition
Physical Review Letters, 2001Co-Authors: S A Moiseev, Stefan KrollAbstract:An idea for how to reconstruct the Quantum State of a nonstationary single-photon wave packet absorbed in a macroscopic medium with inhomogeneously broadened lines is presented. An analytical treatment of the problem is performed and the requirements on the proposed scheme for complete recovery of the recorded nonstationary Quantum State with a probability close to unity is described. The physical nature of the present scheme is also discussed.
Joonwoo Bae - One of the best experts on this subject based on the ideXlab platform.
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structure of minimum error Quantum State discrimination
New Journal of Physics, 2013Co-Authors: Joonwoo BaeAbstract:Distinguishing different Quantum States is a fundamental task having practical applications in information processing. Despite the effort devoted so far, however, strategies for optimal discrimination are known only for specific examples. In this paper we consider the problem of minimum-error Quantum State discrimination where one attempts to minimize the average error. 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 equivalent class that 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.
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structure of minimum error Quantum State discrimination
arXiv: Quantum Physics, 2012Co-Authors: Joonwoo BaeAbstract: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.
Giuseppe Carleo - One of the best experts on this subject based on the ideXlab platform.
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Neural-network Quantum State tomography
Nature Physics, 2018Co-Authors: Giacomo Torlai, Roger Melko, Juan Carrasquilla, Guglielmo Mazzola, Matthias Troyer, Giuseppe CarleoAbstract:The experimental realization of increasingly complex synthetic Quantum systems calls for the development of general theoretical methods to validate and fully exploit Quantum resources. Quantum State tomography (QST) aims to reconstruct the full Quantum State from simple measurements, and therefore provides a key tool to obtain reliable analytics1–3. However, exact brute-force approaches to QST place a high demand on computational resources, making them unfeasible for anything except small systems4,5. Here we show how machine learning techniques can be used to perform QST of highly entangled States with more than a hundred qubits, to a high degree of accuracy. We demonstrate that machine learning allows one to reconstruct traditionally challenging many-body quantities—such as the entanglement entropy—from simple, experimentally accessible measurements. This approach can benefit existing and future generations of devices ranging from Quantum computers to ultracold-atom Quantum simulators6–8.
S A Moiseev - One of the best experts on this subject based on the ideXlab platform.
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complete reconstruction of the Quantum State of a single photon wave packet absorbed by a doppler broadened transition
Physical Review Letters, 2001Co-Authors: S A Moiseev, Stefan KrollAbstract:An idea for how to reconstruct the Quantum State of a nonstationary single-photon wave packet absorbed in a macroscopic medium with inhomogeneously broadened lines is presented. An analytical treatment of the problem is performed and the requirements on the proposed scheme for complete recovery of the recorded nonstationary Quantum State with a probability close to unity is described. The physical nature of the present scheme is also discussed.
R Blatt - One of the best experts on this subject based on the ideXlab platform.
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Quantum State transfer from an ion to a photon
Nature Photonics, 2013Co-Authors: A Stute, Bernardo Casabone, B Brandstatter, Konstantin Friebe, T E Northup, R BlattAbstract:Researchers demonstrate deterministic Quantum-State transfer from a 40Ca+ ion to a photon in an optical cavity by controlling the transition probabilities and the frequency difference of two simultaneous Raman fields. They used process tomography to characterize the Quantum-State transfer, providing a process fidelity of 92% and a State-transfer efficiency of 16%.
