Decoherence-enhanced quantum measurement of a quantum-dot spin qubit

Roszak, Katarzyna; Marcinowski, Łukasz; Machnikowski, Paweł

doi:10.1103/physreva.91.032118

Cited by 5 publications

(6 citation statements)

References 38 publications

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“…In this context, one finds that few-electron quantum dots (QDs) play an important role [4,5]. The usefulness of QDs appears in a wide range of scientific areas spreading from quantum information [6][7][8] to biology and medicine [9]. In late 90s one has noticed that the physical properties of QDs are directly connected with their geometry, i.e.…”

Section: Introductionmentioning

confidence: 99%

Oscillating properties of a two-electron quantum dot in the presence of a magnetic field

Maniero¹,

Carvalho²,

Prudente³

et al. 2020

J. Phys. B: At. Mol. Opt. Phys.

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We give a basic explanation for the oscillating properties of some physical quantities of a two-electron quantum dot in the presence of a static magnetic field. This behaviour was discussed in a previous work of ours [AM Maniero, et al. J. Phys. B: At. Mol. Opt. Phys. 53:185001, 2020] and was identified as a manifestation of the de Haas-van Alphen effect, originally observed in the framework of diamagnetism of metals in the 30's. We show that this behaviour is a consequence of different eigenstates of the system assuming, in a certain interval of the magnetic field, the condition of the lowest energy singlet and triplet states.

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Section: Introductionmentioning

confidence: 99%

Oscillating properties of a two-electron quantum dot in the presence of a magnetic field

Maniero¹,

Carvalho²,

Prudente³

et al. 2020

J. Phys. B: At. Mol. Opt. Phys.

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“…Clearly, depending on the choice of dilation, different SE correlation scenarios are possible, as we will point out next. For pure qubit dephasing studied here, without loss of generality the total unitary evolution can be written in the form [24],…”

Section: Dilating Qubit Dephasingmentioning

confidence: 99%

“…For pure qubit dephasing studied here, without loss of generality the total unitary evolution can be written in the form [24],…”

Section: Dilating Qubit Dephasingmentioning

confidence: 99%

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System-environment correlations for dephasing two-qubit states coupled to thermal baths

2016

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Based on the exact dynamics of a two-qubit system and environment, we investigate system-environment (SE) quantum and classical correlations. The coupling is chosen to represent a dephasing channel for one of the qubits and the environment is a proper thermal bath. First we discuss the general issue of dilation for qubit phase damping. Based on the usual thermal bath of harmonic oscillators, we derive criteria of separability and entanglement between an initial X state and the environment. Applying these criteria to initial Werner states, we find that entanglement between the system and environment is built up in time for temperatures below a certain critical temperature T crit . On the other hand, the total state remains separable during those short times that are relevant for decoherence and loss of entanglement in the two-qubit state. Close to T crit the SE correlations oscillate between separable and entangled. Even though these oscillations are also observed in the entanglement between the two qubits, no simple relation between the loss of entanglement in the two-qubit system and the build-up of entanglement between the system and environment is found.

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“…The problem is that the question of entanglement becomes important when dealing with decoherence between a quantum system of interest, such as a qubit, and its environment. This is because the presence of entanglement, although its manifestation is limited when straightforward qubit decoherence is of interest [14,15], can significantly change the effect that the environment has on the system in more involved procedures and algorithms, especially ones that involve qubit evolution post-measurement [16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

A scheme for direct detection of qubit–environment entanglement generated during qubit pure dephasing

Rzepkowski

Roszak

2020

Quantum Inf Process

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We propose a scheme for the detection of qubit–environment entanglement which requires only operations and measurements on the qubit, all within reach of current experimental state-of-the-art. The scheme works for any type of interaction which leads to pure dephasing of the qubit as long as the initial qubit state is pure. The scheme is direct in the sense that it allows the detection of entanglement present in the system at time $$\tau $$ τ after the initialization of the qubit in a superposition state. It requires a measurement on the qubit at time $$\tau $$ τ and a comparison of the post-measurement evolution to the evolution obtained by a modified scheme. It becomes particularly simple when one of the qubit states is neutral with respect to the environment, such as in case of the most common choice of the NV center spin qubit or for excitonic charge qubits, when the environment is initially at thermal equilibrium. In this case, the post-measurement evolution needs to be compared only to the standard decoherence which is obtained without any qubit manipulation after the preparation of the initial state.

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Decoherence-enhanced quantum measurement of a quantum-dot spin qubit

Cited by 5 publications

References 38 publications

Oscillating properties of a two-electron quantum dot in the presence of a magnetic field

Oscillating properties of a two-electron quantum dot in the presence of a magnetic field

System-environment correlations for dephasing two-qubit states coupled to thermal baths

A scheme for direct detection of qubit–environment entanglement generated during qubit pure dephasing

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