Protecting entanglement from decoherence using weak measurement and quantum measurement reversal

Kim, Yong‐Su; Lee, Jong-Chan; Kwon, Oh‐Min

doi:10.1117/12.2024442

Cited by 47 publications

(77 citation statements)

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“…Bob 20,21,23). After Alice's WM and Bob's RM, entanglement in the two-qubit is quantified by concurrence…”

Section: Resultsmentioning

confidence: 99%

“…The WM and the RM are implemented with wave plates and Brewster's angle glass plates 25 . The final two-qubit state is analysed with wave plates and polarizers via two-qubit quantum state tomography 23 .…”

Section: Resultsmentioning

confidence: 99%

“…Note that wave plates are used to compensate polarization rotation by SMFs at each SMF output. The Markovian amplitude damping decoherence (D) is set up with a displaced Sagnac interferometer 21,23 . The WM and the RM are implemented with wave plates and Brewster's angle glass plates 25 .…”

Section: Resultsmentioning

confidence: 99%

“…In contrast to the normal decoherence suppression scheme [20][21][22][23] , in which the choice whether or not to suppress decoherence is naturally made before the decoherence by the initial weak measurement (WM), our decoherence suppression scheme delays the choice after the decoherence itself. We demonstrate that although the choice to suppress decoherence is made by delayed WM after the decoherence and even after detection of the quantum system, our scheme can suppress decoherence successfully.…”

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confidence: 99%

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Experimental demonstration of delayed-choice decoherence suppression

et al. 2014

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Wheeler's delayed-choice experiment illustrates vividly that the observer plays a central role in quantum physics by demonstrating that complementarity or wave-particle duality can be enforced even after the photon has already entered the interferometer. The delayed-choice quantum eraser experiment further demonstrates that complementarity can be enforced even after detection of a quantum system, elucidating the foundational nature of complementarity in quantum physics. However, the applicability of the delayed-choice method for practical quantum information protocols continues to be an open question. Here, we introduce and experimentally demonstrate the delayed-choice decoherence suppression protocol, in which the decision to suppress decoherence on an entangled two-qubit state is delayed until after the decoherence and even after the detection of a qubit. Our result suggests a new way to tackle Markovian decoherence in a delayed manner, applicable for practical entanglement distribution over a dissipative channel.

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“…Bob 20,21,23). After Alice's WM and Bob's RM, entanglement in the two-qubit is quantified by concurrence…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Experimental demonstration of delayed-choice decoherence suppression

et al. 2014

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“…In experimental realizations of error correction procedures, the effect of the measurement is implicitly reversed but its outcome remains unknown. Previous realizations of measurement reversal with known outcomes have been performed in the context of weak measurements where the measurement and its reversal are probabilistic processes [8][9][10][11]. We will show that it is possible to deterministically reverse measurements on a single particle.…”

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Undoing a Quantum Measurement

et al. 2013

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In general, a quantum measurement yields an undetermined answer and alters the system to be consistent with the measurement result. This process maps multiple initial states into a single state and thus cannot be reversed. This has important implications in quantum information processing, where errors can be interpreted as measurements. Therefore, it seems that it is impossible to correct errors in a quantum information processor, but protocols exist that are capable of eliminating them if they affect only part of the system. In this work we present the deterministic reversal of a fully projective measurement on a single particle, enabled by a quantum error-correction protocol that distributes the information over three particles.Measurements on a quantum system irreversibly project the system onto a measurement eigenstate regardless of the state of the system. Copying an unknown quantum state is thus impossible because learning about a state without destroying it is prohibited by the nocloning theorem [1]. At first, this seems to be a roadblock for correcting errors in quantum information processors. However, the quantum information can be encoded redundantly in multiple particles and subsequently used by quantum error correction (QEC) techniques [2][3][4][5][6][7]. When one interprets errors as measurements, it becomes clear that such protocols are able to reverse a partial measurement on the system. In experimental realizations of error correction procedures, the effect of the measurement is implicitly reversed but its outcome remains unknown. Previous realizations of measurement reversal with known outcomes have been performed in the context of weak measurements where the measurement and its reversal are probabilistic processes [8][9][10][11]. We will show that it is possible to deterministically reverse measurements on a single particle.We consider a system of three two-level atoms where each can be described as a qubit with the basis states |0 , |1 . An arbitrary pure single-qubit quantum state is given by |ψ = α|0 + β|1 with |α| 2 + |β| 2 = 1 and α, β ∈ C. In the used error-correction protocol, the information of a single (system) qubit is distributed over three qubits by storing the information redundantly in the state α|000 + β|111 . This encoding is able to correct a single bit-flip by performing a majority vote and is known as the repetition code [12].A measurement in the computational basis states |0 , |1 causes a projection onto the σ z axis of the Bloch sphere and can be interpreted as an incoherent phase flip. Thus, any protocol correcting against phase-flips is sufficient to reverse measurements in the computational basis. The repetition code can be modified to protect against such phase-flip errors by a simple basis change from |0 , |1 to |± = 1/ √ 2(|0 ± |1 ). After this basis change each individual qubit is in an equal superposition of |0 and |1 and therefore it is impossible to gain any information about the encoded quantum information by measuring a single qubit along σ z . Because the repet...

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Entanglement Sudden Death and Birth Effects in Two Qubits Maximally Entangled Mixed States Under Quantum Channels

Sharma

Gerdt

2019

Int J Theor Phys

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In the present article, the robustness of entanglement in two qubits maximally entangled mixed states (MEME) have been studied under quantum decoherence channels. Here we consider bit flip, phase flip, bit-phase-flip, amplitude damping, phase damping and depolarization channels. To quantify the entanglement, the concurrence has been used as an entanglement measure. During this study interesting results have been found for sudden death and birth of entanglement under bit flip and bit-phase-flip channels. While amplitude damping channel produces entanglement sudden death and does not allow re-birth of entanglement. On the other hand, two qubits MEMS exhibit the robust character against the phase flip, phase damping and depolarization channels. The elegant behavior of all the quantum channels have been investigated with varying parameter of quantum state MEMS in different cases.

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Protecting entanglement from decoherence using weak measurement and quantum measurement reversal

Cited by 47 publications

References 0 publications

Experimental demonstration of delayed-choice decoherence suppression

Experimental demonstration of delayed-choice decoherence suppression

Undoing a Quantum Measurement

Entanglement Sudden Death and Birth Effects in Two Qubits Maximally Entangled Mixed States Under Quantum Channels

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