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Mark M. Wilde - One of the best experts on this subject based on the ideXlab platform.
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fidelity of Recovery squashed entanglement and measurement recoverability
Physical Review A, 2015Co-Authors: Kaushik P Seshadreesan, Mark M. WildeAbstract:This paper defines the fidelity of Recovery of a tripartite quantum state on systems $A,\phantom{\rule{0.16em}{0ex}}B$, and $C$ as a measure of how well one can recover the full state on all three systems if system $A$ is lost and a Recovery Operation is performed on system $C$ alone. The surprisal of the fidelity of Recovery (its negative logarithm) is an information quantity which obeys nearly all of the properties of the conditional quantum mutual information $I(A;B|C)$, including non-negativity, monotonicity with respect to local Operations, duality, invariance with respect to local isometries, a dimension bound, and continuity. We then define a (pseudo) entanglement measure based on this quantity, which we call the ``geometric squashed entanglement.'' We prove that the geometric squashed entanglement is a 1-LOCC monotone (i.e., monotone nonincreasing with respect to local Operations and classical communication from Bob to Alice), that it vanishes if and only if the state on which it is evaluated is unentangled, and that it reduces to the geometric measure of entanglement if the state is pure. We also show that it is invariant with respect to local isometries, subadditive, continuous, and normalized on maximally entangled states. We next define the surprisal of measurement recoverability, which is an information quantity in the spirit of quantum discord, characterizing how well one can recover a share of a bipartite state if it is measured. We prove that this discordlike quantity satisfies several properties, including non-negativity, faithfulness on classical-quantum states, invariance with respect to local isometries, a dimension bound, and normalization on maximally entangled states. This quantity, combined with a recent breakthrough of Fawzi and Renner, makes it possible to characterize states with discord nearly equal to zero as being approximate fixed points of entanglement-breaking channels (equivalently, they are recoverable from the state of a measuring apparatus). Finally, we discuss a multipartite fidelity of Recovery and several of its properties.
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fidelity of Recovery squashed entanglement and measurement recoverability
Physical Review A, 2015Co-Authors: Kaushik P Seshadreesan, Mark M. WildeAbstract:This paper defines the fidelity of Recovery of a quantum state on systems $A$, $B$, and $C$ as a measure of how well one can recover the full state on all three systems if system $A$ is lost and a Recovery Operation is performed on system $C$ alone. The surprisal of the fidelity of Recovery (its negative logarithm) is an information quantity which obeys nearly all of the properties of the conditional quantum mutual information $I(A;B|C)$, including non-negativity, monotonicity with respect to local Operations, duality, invariance with respect to local isometries, a dimension bound, and continuity. We then define a (pseudo) entanglement measure based on this quantity, which we call the geometric squashed entanglement. We prove that the geometric squashed entanglement is a 1-LOCC monotone, that it vanishes if and only if the state on which it is evaluated is unentangled, and that it reduces to the geometric measure of entanglement if the state is pure. We also show that it is invariant with respect to local isometries, subadditive, continuous, and normalized on maximally entangled states. We next define the surprisal of measurement recoverability, which is an information quantity in the spirit of quantum discord, characterizing how well one can recover a share of a bipartite state if it is measured. We prove that this discord-like quantity satisfies several properties, including non-negativity, faithfulness on classical-quantum states, invariance with respect to local isometries, a dimension bound, and normalization on maximally entangled states. This quantity combined with a recent breakthrough of Fawzi and Renner allows to characterize states with discord nearly equal to zero as being approximate fixed points of entanglement breaking channels. Finally, we discuss a multipartite fidelity of Recovery and several of its properties.
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recoverability in quantum information theory
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2015Co-Authors: Mark M. WildeAbstract:The fact that the quantum relative entropy is non-increasing with respect to quantum physical evolutions lies at the core of many optimality theorems in quantum information theory and has applications in other areas of physics. In this work, we establish improvements of this entropy inequality in the form of physically meaningful remainder terms. One of the main results can be summarized informally as follows: if the decrease in quantum relative entropy between two quantum states after a quantum physical evolution is relatively small, then it is possible to perform a Recovery Operation, such that one can perfectly recover one state while approximately recovering the other. This can be interpreted as quantifying how well one can reverse a quantum physical evolution. Our proof method is elementary, relying on the method of complex interpolation, basic linear algebra and the recently introduced Renyi generalization of a relative entropy difference. The theorem has a number of applications in quantum information theory, which have to do with providing physically meaningful improvements to many known entropy inequalities.
Kaushik P Seshadreesan - One of the best experts on this subject based on the ideXlab platform.
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fidelity of Recovery squashed entanglement and measurement recoverability
Physical Review A, 2015Co-Authors: Kaushik P Seshadreesan, Mark M. WildeAbstract:This paper defines the fidelity of Recovery of a quantum state on systems $A$, $B$, and $C$ as a measure of how well one can recover the full state on all three systems if system $A$ is lost and a Recovery Operation is performed on system $C$ alone. The surprisal of the fidelity of Recovery (its negative logarithm) is an information quantity which obeys nearly all of the properties of the conditional quantum mutual information $I(A;B|C)$, including non-negativity, monotonicity with respect to local Operations, duality, invariance with respect to local isometries, a dimension bound, and continuity. We then define a (pseudo) entanglement measure based on this quantity, which we call the geometric squashed entanglement. We prove that the geometric squashed entanglement is a 1-LOCC monotone, that it vanishes if and only if the state on which it is evaluated is unentangled, and that it reduces to the geometric measure of entanglement if the state is pure. We also show that it is invariant with respect to local isometries, subadditive, continuous, and normalized on maximally entangled states. We next define the surprisal of measurement recoverability, which is an information quantity in the spirit of quantum discord, characterizing how well one can recover a share of a bipartite state if it is measured. We prove that this discord-like quantity satisfies several properties, including non-negativity, faithfulness on classical-quantum states, invariance with respect to local isometries, a dimension bound, and normalization on maximally entangled states. This quantity combined with a recent breakthrough of Fawzi and Renner allows to characterize states with discord nearly equal to zero as being approximate fixed points of entanglement breaking channels. Finally, we discuss a multipartite fidelity of Recovery and several of its properties.
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fidelity of Recovery squashed entanglement and measurement recoverability
Physical Review A, 2015Co-Authors: Kaushik P Seshadreesan, Mark M. WildeAbstract:This paper defines the fidelity of Recovery of a tripartite quantum state on systems $A,\phantom{\rule{0.16em}{0ex}}B$, and $C$ as a measure of how well one can recover the full state on all three systems if system $A$ is lost and a Recovery Operation is performed on system $C$ alone. The surprisal of the fidelity of Recovery (its negative logarithm) is an information quantity which obeys nearly all of the properties of the conditional quantum mutual information $I(A;B|C)$, including non-negativity, monotonicity with respect to local Operations, duality, invariance with respect to local isometries, a dimension bound, and continuity. We then define a (pseudo) entanglement measure based on this quantity, which we call the ``geometric squashed entanglement.'' We prove that the geometric squashed entanglement is a 1-LOCC monotone (i.e., monotone nonincreasing with respect to local Operations and classical communication from Bob to Alice), that it vanishes if and only if the state on which it is evaluated is unentangled, and that it reduces to the geometric measure of entanglement if the state is pure. We also show that it is invariant with respect to local isometries, subadditive, continuous, and normalized on maximally entangled states. We next define the surprisal of measurement recoverability, which is an information quantity in the spirit of quantum discord, characterizing how well one can recover a share of a bipartite state if it is measured. We prove that this discordlike quantity satisfies several properties, including non-negativity, faithfulness on classical-quantum states, invariance with respect to local isometries, a dimension bound, and normalization on maximally entangled states. This quantity, combined with a recent breakthrough of Fawzi and Renner, makes it possible to characterize states with discord nearly equal to zero as being approximate fixed points of entanglement-breaking channels (equivalently, they are recoverable from the state of a measuring apparatus). Finally, we discuss a multipartite fidelity of Recovery and several of its properties.
Tomohide Terashima - One of the best experts on this subject based on the ideXlab platform.
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great impact of rfc technology on fast Recovery diode towards 600 v for low loss and high dynamic ruggedness
International Symposium on Power Semiconductor Devices and IC's, 2012Co-Authors: Fumihito Masuoka, Katsumi Nakamura, Akito Nishii, Tomohide TerashimaAbstract:In the fast Recovery Operation of Free-wheeling Diode (FWD), to reduce voltage surge “snap-off”, we propose the Relaxed Field of Cathode (RFC)-planar anode diode in the range of 600 V to 1700 V. RFC effect is described by the parallel connection of pin diode and pnp transistor in as a single chip solution. Its structure is realized by our thin wafer process technology utilizing the backside lithography to make p/n alternating pattern after thining the wafer. As the result, our RFC diode up to 1700 V has the following three advantages comparing with the conventional one: (a) 40% lower Recovery loss (EREC), 30% lower forward voltage drop (VF), (b) a large Recovery Safe Operating Area (SOA) with the high peak power density of 1.4W/cm2 and (c) easiness to adjust a lower crosspoint below rated current density in the output I–V. Therefore, the proposed RFC diode has a great potential as the next generation Si FWD in the all voltage range.
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relaxation of current filament due to rfc technology and ballast resistor for robust fwd Operation
International Symposium on Power Semiconductor Devices and IC's, 2011Co-Authors: Akito Nishii, Fumihito Masuoka, K Nakamura, Tomohide TerashimaAbstract:We have investigated the destruction mechanism of High Voltage (HV) Free Wheeling Diodes (FWD) during a reverse Recovery Operation. The most possible mode of the destruction phenomena originate in local heating due to current filament at the edge portion of the active area. To achieve a large reverse Recovery Safe Operation Area (SOA), we focus on the boundary region between the active area and the termination area. To enforce our Relaxed Field of Cathode (RFC) concept [1, 2], it is more effective for the wider SOA to place a ballast resistance for avoiding the current from crowding around the anode region in the top surface of the diode.
Moe Z Win - One of the best experts on this subject based on the ideXlab platform.
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optimum quantum error Recovery using semidefinite programming
Physical Review A, 2007Co-Authors: Andrew S Fletcher, Peter W Shor, Moe Z WinAbstract:Quantum error correction QEC is an essential element of physical quantum information processing systems. Most QEC efforts focus on extending classical error correction schemes to the quantum regime. The input to a noisy system is embedded in a coded subspace, and error Recovery is performed via an Operation designed to perfectly correct for a set of errors, presumably a large subset of the physical noise process. In this paper, we examine the choice of Recovery Operation. Rather than seeking perfect correction on a subset of errors, we seek a Recovery Operation to maximize the entanglement fidelity for a given input state and noise model. In this way, the Recovery Operation is optimal for the given encoding and noise process. This optimization is shown to be calculable via a semidefinite program, a well-established form of convex optimization with efficient algorithms for its solution. The error Recovery Operation may also be interpreted as a combining Operation following a quantum spreading channel, thus providing a quantum analogy to the classical diversity combining Operation.
Fumihito Masuoka - One of the best experts on this subject based on the ideXlab platform.
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great impact of rfc technology on fast Recovery diode towards 600 v for low loss and high dynamic ruggedness
International Symposium on Power Semiconductor Devices and IC's, 2012Co-Authors: Fumihito Masuoka, Katsumi Nakamura, Akito Nishii, Tomohide TerashimaAbstract:In the fast Recovery Operation of Free-wheeling Diode (FWD), to reduce voltage surge “snap-off”, we propose the Relaxed Field of Cathode (RFC)-planar anode diode in the range of 600 V to 1700 V. RFC effect is described by the parallel connection of pin diode and pnp transistor in as a single chip solution. Its structure is realized by our thin wafer process technology utilizing the backside lithography to make p/n alternating pattern after thining the wafer. As the result, our RFC diode up to 1700 V has the following three advantages comparing with the conventional one: (a) 40% lower Recovery loss (EREC), 30% lower forward voltage drop (VF), (b) a large Recovery Safe Operating Area (SOA) with the high peak power density of 1.4W/cm2 and (c) easiness to adjust a lower crosspoint below rated current density in the output I–V. Therefore, the proposed RFC diode has a great potential as the next generation Si FWD in the all voltage range.
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relaxation of current filament due to rfc technology and ballast resistor for robust fwd Operation
International Symposium on Power Semiconductor Devices and IC's, 2011Co-Authors: Akito Nishii, Fumihito Masuoka, K Nakamura, Tomohide TerashimaAbstract:We have investigated the destruction mechanism of High Voltage (HV) Free Wheeling Diodes (FWD) during a reverse Recovery Operation. The most possible mode of the destruction phenomena originate in local heating due to current filament at the edge portion of the active area. To achieve a large reverse Recovery Safe Operation Area (SOA), we focus on the boundary region between the active area and the termination area. To enforce our Relaxed Field of Cathode (RFC) concept [1, 2], it is more effective for the wider SOA to place a ballast resistance for avoiding the current from crowding around the anode region in the top surface of the diode.
