Coherent charge qubits based on GaAs quantum dots with a built-in barrier

Fedichkin, Leonid; Yanchenko, M.; Valiev, K. A.

doi:10.1088/0957-4484/11/4/339

Cited by 105 publications

(107 citation statements)

References 4 publications

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“…As in the case of the short-time approximation, we get the upper bound for the multiqubit norm D(t), (53).…”

Section: Spin Model For Pure Decoherencementioning

confidence: 99%

Evaluation of Decoherence for Quantum Control and Computing

Fedorov¹,

Fedichkin²,

Privman³

2004

Jnl of Comp & Theo Nano

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Different approaches in quantifying environmentally-induced decoherence are considered. We identify a measure of decoherence, derived from the density matrix of the system of interest, that quantifies the environmentally induced error, i.e., deviation from the ideal isolated-system dynamics. This measure can be shown to have several useful features. Its behavior as a function of time has no dependence on the initial conditions, and is expected to be insensitive to the internal dynamical time scales of the system, thus only probing the decoherence-related time dependence.For a spin-boson model-a prototype of a qubit interacting with environment-we also demonstrate the property of additivity: in the regime of the onset of decoherence, the sum of the individual qubit error measures provides an estimate of the error for a several-qubit system, even if the qubits are entangled, as expected in quantum-computing applications. This makes it possible to estimate decoherence for several-qubits quantum computer gate designs for which explicit calculations are exceedingly difficult.

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“…As in the case of the short-time approximation, we get the upper bound for the multiqubit norm D(t), (53).…”

Section: Spin Model For Pure Decoherencementioning

confidence: 99%

Evaluation of Decoherence for Quantum Control and Computing

Fedorov¹,

Fedichkin²,

Privman³

2004

Jnl of Comp & Theo Nano

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show abstract

“…5 Such scheme, however, is based on the variability of the tunneling. 9,10,11 In many physical quantum systems, the handle on the tunneling is limited or impossible. Then the implementation of full single-qubit manipulation requires tunable external magnetic fields and the architecture of the system must be elaborately designed.…”

Section: Introductionmentioning

confidence: 99%

Aharonov-Bohm phase operations on a double-barrier nanoring charge qubit

Wang

Zhu

2006

Phys. Rev. B

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We present a scheme for charge qubit implementation in a double-barrier nanoring. The logical states of the qubit are encoded in the spatial wavefunctions of the two lowest energy states of the system. The Aharonov-Bohm phase introduced by magnetic flux, instead of tunable tunnelings, along with electric fields can be used for implementing the quantum gate operations. During the operations, the external fields should be switched smoothly enough to avoid the errors caused by the transition to higher-lying states. The structure and field effects on the validity of the qubit are also studied.

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“…In order to define qubits in lateral quantum dot (QD) structures, the two degrees of freedom, spin and charge, are naturally used. For spin qubits 5 , the information is encoded in the spin of a single electron in one quantum dot, whereas for the charge qubit 6,7,8 the position of a single electron in a double dot system defines the logical states. Similar ideas can also be applied to charge states in Silicon donors 9 .…”

Section: Introductionmentioning

confidence: 99%

Intrinsic phonon decoherence and quantum gates in coupled lateral quantum-dot charge qubits

et al. 2005

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Recent experiments by Hayashi et al. [Phys. Rev. Lett. 91, 226804 (2003)] demonstrate coherent oscillations of a charge quantum bit (qubit) in laterally defined quantum dots. We study the intrinsic electron-phonon decoherence and gate performance for the next step: a system of two coupled charge qubits. The effective decoherence model contains properties of local as well as collective decoherence. Decoherence channels can be classified by their multipole moments, which leads to different lowenergy spectra. It is shown that due to the super-Ohmic spectrum, the gate quality is limited by the single-qubit Hadamard gates. It can be significantly improved, by using double-dots with weak tunnel coupling.

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Coherent charge qubits based on GaAs quantum dots with a built-in barrier

Cited by 105 publications

References 4 publications

Evaluation of Decoherence for Quantum Control and Computing

Evaluation of Decoherence for Quantum Control and Computing

Aharonov-Bohm phase operations on a double-barrier nanoring charge qubit

Intrinsic phonon decoherence and quantum gates in coupled lateral quantum-dot charge qubits

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