Non-Markovian dynamics and noise characteristics in continuous measurement of a solid-state charge qubit

Luo, Jun; Jiao, HuJun; Xiong, Bo; He, Xiaoyong; Wang, Changrong

doi:10.1063/1.4828870

Cited by 5 publications

(3 citation statements)

References 73 publications

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“…Typically, the state of a solid state qubit could be indirectly extracted by measuring the conductance of a current carrying electro-meter which is capacitively coupled to the qubit. This detector, which could be realized in the experiment by a quantum point contact(QPC) [1][2][3][4][5][6][7][8] or a single electron transistor(SET) [9][10][11][12][13][14][15][16] , provides us with measurements of the charge fluctuations of qubit. The usage of SETs are however more advantageous to the QPCs because of their much more sensitivity to the charge fluctuations 16 .…”

Section: Introductionmentioning

confidence: 99%

Perturbative approach to the capacitive interaction between a sensor quantum dot and a charge qubit

Tabatabaei

2017

Phys. Rev. B

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We consider the capacitive interaction between a charge qubit and a sensor quantum dot(SQD) perturbatively to the second order of their coupling constant at zero temperature by utilizing the method of non-equilibrium Green's functions together with infinite-U Lacroix approximation and employing Majorana fermion representation for qubit isospin operators. The effect of back-actions on dynamics of the system is taken into account by calculating the self-energies and the Green's functions in a self-consistent manner. To demonstrate the applicability of the method, we investigate relevant physical quantities of the system at zero and finite bias voltages. In the regime of weak SQD-qubit coupling, we find a linear relation between the stationary-state expectation values of the third component of the qubit isospin vector, τ3 , and the differential conductance of the SQD. Furthermore, our numerical results predict that the effect of SQD-qubit coupling on differential conductance of the SQD should be maximized at zero bias voltage. Moreover, we obtain an analytical expression to describe the behavior of the differential conductance of the SQD with respect to the qubit parameters. Our results at zero bias voltage are consistent with the results of numerical renormalization group method.

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Section: Introductionmentioning

confidence: 99%

Perturbative approach to the capacitive interaction between a sensor quantum dot and a charge qubit

Tabatabaei

2017

Phys. Rev. B

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“…Normally, they fall into two categories. The first type is based on the enhancement of measurement signal by employing approaches such as quantum nondemolition measurements [70,71], non-Markovian memory effect [72], or quantum feedback scheme [73,74]. The second on concerns with the reduction of the noise pedestal by utilizing twin detectors [45,75], or strongly responding detectors [20].…”

Section: Measurement Effectivenessmentioning

confidence: 99%

Qubit detection with a T-shaped double quantum dot detector

Luo

Jiao

et al. 2015

Phys. Rev. B

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We propose to continuously monitor a charge qubit by utilizing a T-shaped double quantum dot detector, in which the qubit and double dot are arranged in such a unique way that the detector turns out to be particularly susceptible to the charge states of the qubit. Special attention is paid to the regime where acquisition of qubit information and backaction upon the measured system exhibit nontrivial correlation. The intrinsic dynamics of the qubit gives rise to dynamical blockade of tunneling events through the detector, resulting in a super-Poissonian noise. However, such a pronounced enhancement of detector's shot noise does not necessarily produce a rising dephasing rate. In contrast, an inhibition of dephasing is entailed by the reduction of information acquisition in the dynamically blockaded regimes. We further reveal the important impact of the charge fluctuations on the measurement characteristics. Noticeably, under the condition of symmetric junction capacitances the noise pedestal of circuit current is completely suppressed, leading to a divergent signal-to-noise ratio, and eventually to a violation of the Korotkov-Averin bound in quantum measurement. Our study offers the possibility for a double dot detector to reach the quantum limited effectiveness in a transparent manner.

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“…This approach has been widely employed to analyze the FCS in a variety of structures, for instance, quantum dot (QD) systems [29][30][31][32][33][34][35], molecules [36][37][38][39][40], and nanoelectromechanical resonators [41][42][43]. Furthermore, the QME approach was recently extended to investigate finite-frequency FCS [44,45] as well as nonMarkovian dynamics [46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Conditional spin counting statistics as a probe of Coulomb interaction and spin-resolved bunching

Luo

Lang

et al. 2014

Physics Letters A

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Full counting statistics is a powerful tool to characterize the noise and correlations in transport through mesoscopic systems. In this work, we propose the theory of conditional spin counting statistics, i.e., the statistical fluctuations of spin-up (down) current given the observation of the spindown (up) current. In the context of transport through a single quantum dot, it is demonstrated that a strong Coulomb interaction leads to a conditional spin counting statistics that exhibits a substantial change in comparison to that without Coulomb repulsion. It thus can be served as an effective way to probe the Coulomb interactions in mesoscopic transport systems. In case of spin polarized transport, it is further shown that the conditional spin counting statistics offers a transparent tool to reveal the spin-resolved bunching behavior.

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Non-Markovian dynamics and noise characteristics in continuous measurement of a solid-state charge qubit

Cited by 5 publications

References 73 publications

Perturbative approach to the capacitive interaction between a sensor quantum dot and a charge qubit

Perturbative approach to the capacitive interaction between a sensor quantum dot and a charge qubit

Qubit detection with a T-shaped double quantum dot detector

Conditional spin counting statistics as a probe of Coulomb interaction and spin-resolved bunching

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