Quantum measurement of coherent tunneling between quantum dots

Wiseman, Howard Mark; Utami, Dian Wahyu; Sun, He-Bi; Milburn, G. J.; Kane, B. E.; Dzurak, Andrew S.; Clark, Robert G.

doi:10.1103/physrevb.63.235308

Cited by 30 publications

(82 citation statements)

References 19 publications

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“…For the single-particle parity measurement, a misplaced SET island produces a measurement in the localized basis, which has been discussed in the past. 19 The two-particle singlet-triplet measurement scheme is less sensitive to asymmetry in the placement of the SET, but requires very low temperatures to work effectively.…”

Section: Discussionmentioning

confidence: 99%

“…This forms a generalization of the results of Wiseman et al 19 to the situation where the measurement Hamiltonian (H CB in their notation) does not commute with the free Hamiltonian of the system (H 0 in their notation). Equation (C11) shows the importance of the Fourier decomposition of the system operator B k ͑t͒-the Fourier components of B k ͑t͒, and their adjoint, form the Lindblad operators in the master equation, and it is through these components that the DWS interacts with the SET island.…”

mentioning

confidence: 98%

“…Following the derivation of Wiseman et al, 19 we can write down a master equation for the reduced density matrix, R, for the system consisting of the double well plus the SET island. The dissipative terms are formally the same, where we identify c + and c s , respectively, with c 1 and b in their notation.…”

Section: Appendix A: Master Equation For Symmetric Single Particle Symentioning

confidence: 99%

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Parity measurement of one- and two-electron double well systems

et al. 2004

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We outline a scheme to accomplish measurements of a solid state double well system (DWS) with both one and two electrons in nonlocalized bases. We show that, for a single particle, measuring the local charge distribution at the midpoint of a DWS using a SET as a sensitive electrometer amounts to performing a projective measurement in the parity (symmetric/antisymmetric) eigenbasis. For two-electrons in a DWS, a similar configuration of SET results in close-to-projective measurement in the singlet/triplet basis. We analyze the sensitivity of the scheme to asymmetry in the SET position for some experimentally relevant parameter, and show that it is experimentally realizable.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 98%

Section: Appendix A: Master Equation For Symmetric Single Particle Symentioning

confidence: 99%

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Parity measurement of one- and two-electron double well systems

et al. 2004

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“…Prime examples are the mesoscopic measurement devices used in quantum electronics, such as single electron transistors. This device has received much attention as a possible measurement device for solid state qubits [35,36,37]. Conditional states may be used in quantum computation both for preparation, and for nondeterministic gate implementation [38].…”

Section: Discussionmentioning

confidence: 99%

Quantum trajectories for realistic photodetection: I. General formalism

Warszawski

Wiseman

2002

J. Opt. B: Quantum Semiclass. Opt.

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Quantum trajectories describe the stochastic evolution of an open quantum system conditioned on continuous monitoring of its output, such as by an ideal photodetector. In practice an experimenter has access to an output filtered through various electronic devices, rather than the microscopic states of the detector. This introduces several imperfections into the measurement process, of which only inefficiency has previously been incorporated into quantum trajectory theory. However, all electronic devices have finite bandwidths, and the consequent delay in conveying the output signal to the observer implies that the evolution of the conditional state of the quantum system must be non-Markovian. We present a general method of describing this evolution and apply it to avalanche photodiodes (APDs) and to photoreceivers. We include the effects of efficiency, dead time, bandwidth, electronic noise, and dark counts. The essential idea is to treat the quantum system and classical detector jointly, and to average over the latter to obtain the conditional quantum state. The significance of our theory is that quantum trajectories for realistic detection are necessary for sophisticated approaches to quantum feedback, and our approach could be applied in many areas of physics.

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“…Quantum trajectory theory 6,7,8 has been used to describe single realizations of the continuous-intime weak quantum measurement of electronic charge qubits 9,10,11,12,13,14,15,16,17,18,19 conditioned by the electrical output of a mesoscopic measurement device such as a quantum point contact (QPC) or single-electron transistor (SET). Very recently, quantum trajectory theory has been applied to circuit QED.…”

Section: Introductionmentioning

confidence: 99%

Model for monitoring of a charge qubit using a radio-frequency quantum point contact including experimental imperfections

2008

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The extension of quantum trajectory theory to incorporate realistic imperfections in the measurement of solid-state qubits is important for quantum computation, particularly for the purposes of state preparation and error-correction as well as for readout of computations. Previously this has been achieved for low-frequency (dc) weak measurements. In this paper we extend realistic quantum trajectory theory to include radio frequency (rf) weak measurements where a low-transparency quantum point contact (QPC), coupled to a charge qubit, is used to damp a classical oscillator circuit. The resulting realistic quantum trajectory equation must be solved numerically. We present an analytical result for the limit of large dissipation within the oscillator (relative to the QPC), where the oscillator slaves to the qubit. The rf+dc mode of operation is considered. Here the QPC is biased (dc) as well as subjected to a small-amplitude sinusoidal carrier signal (rf). The rf+dc QPC is shown to be a low-efficiency charge qubit detector, that may nevertheless be higher than the dc-QPC (which is subject to 1/f noise).

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Quantum measurement of coherent tunneling between quantum dots

Cited by 30 publications

References 19 publications

Parity measurement of one- and two-electron double well systems

Parity measurement of one- and two-electron double well systems

Quantum trajectories for realistic photodetection: I. General formalism

Model for monitoring of a charge qubit using a radio-frequency quantum point contact including experimental imperfections

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