Principles and applications of quantum control engineering

Gough, John E.

doi:10.1098/rsta.2012.0370

Cited by 28 publications

(26 citation statements)

References 54 publications

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“…1 can be derived using the cascaded cavity theory of Gardiner and Carmichael [19,20], or by the modern SLH quantum network theory [21,23]. We utilize the latter here and Fig.…”

Section: A Full Model Of Cascaded Cavitiesmentioning

confidence: 99%

“…The output field z(t) emerges from the output port of cavity 2 and is monitored by homodyne detection (see below). The SLH triples (S, L, H) [21,23,24] for these blocks are H c describes the effective direct coupling of the two cavity modes due to the probe field that interacts with both cavities. Similarly, the effective drives for the cavity modes in H d are composed of the probe field¯ (t) and the drive fields entering the input ports.…”

Section: A Full Model Of Cascaded Cavitiesmentioning

confidence: 99%

“…Section II A presents the dynamical model for full system derived from cascaded systems theory [19][20][21]. Then in section II B we perform a two-cavity polaron transformation on the model to obtain an exact, dressed description for the qubits alone that is easier to simulate than the full dynamical model.…”

Section: Introductionmentioning

confidence: 99%

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Continuous joint measurement and entanglement of qubits in remote cavities

2015

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We present a first principles theoretical analysis of the entanglement of two superconducting qubits in spatially separated microwave cavities by a sequential (cascaded) probe of the two cavities with a coherent mode, that provides a full characterization of both the continuous measurement induced dynamics and the entanglement generation. We use the SLH formalism to derive the full quantum master equation for the coupled qubits and cavities system, within the rotating wave and dispersive approximations, and conditioned equations for the cavity fields. We then develop effective stochastic master equations for the dynamics of the qubit system in both a polaronic reference frame and a reduced representation within the laboratory frame. We compare simulations with and analyze tradeoffs between these two representations, including the onset of a non-Markovian regime for simulations in the reduced representation. We provide conditions for ensuring persistence of entanglement and show that using shaped pulses enables these conditions to be met at all times under general experimental conditions. The resulting entanglement is shown to be robust with respect to measurement imperfections and loss channels. We also study the effects of qubit driving and relaxation dynamics during a weak measurement, as a prelude to modeling measurement-based feedback control in this cascaded system.

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“…1 can be derived using the cascaded cavity theory of Gardiner and Carmichael [19,20], or by the modern SLH quantum network theory [21,23]. We utilize the latter here and Fig.…”

Section: A Full Model Of Cascaded Cavitiesmentioning

confidence: 99%

Section: A Full Model Of Cascaded Cavitiesmentioning

confidence: 99%

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Continuous joint measurement and entanglement of qubits in remote cavities

2015

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“…Surveys of control theoretic achievements can be found, for example, in [159][160][161]. Optimal control techniques have also been successfully applied to multi-dimensional nuclear magnetic resonance targeting at improving the sensitivity of these systems [162,163].…”

Section: Quantum Controlmentioning

confidence: 99%

Horizons of cybernetical physics

Fradkov

2017

Phil. Trans. R. Soc. A.

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The subject and main areas of a new research field—cybernetical physics—are discussed. A brief history of cybernetical physics is outlined. The main areas of activity in cybernetical physics are briefly surveyed, such as control of oscillatory and chaotic behaviour, control of resonance and synchronization, control in thermodynamics, control of distributed systems and networks, quantum control. This article is part of the themed issue ‘Horizons of cybernetical physics’.

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“…Feedback control of quantum mechanical systems is a rapidly emerging topic [1,2], developed most fully in the field of quantum optics [3]. Only recently have these ideas been extended to quantum transport, a field which looks to understand and control the motion of electrons through structures on the nano-scale [4].…”

Section: Introductionmentioning

confidence: 99%

Feedback Control in Quantum Transport

Emary

2016

Understanding Complex Systems

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Abstract. Quantum transport is the study of the motion of electrons through nano-scale structures small enough that quantum effects are important. In this contribution I review recent theoretical proposals to use the techniques of quantum feedback control to manipulate the properties of electron flows and states in quantum-transport devices. Quantum control strategies can be grouped into two broad classes: measurement-based control and coherent control, and both are covered here. I discuss how measurement-based techniques are capable of producing a range of effects, such as noise suppression, stabilisation of nonequillibrium quantum states and the realisation of a nano-electronic Maxwell's demon. I also describe recent results on coherent transport control and its relation to quantum networks. IntroductionFeedback control of quantum mechanical systems is a rapidly emerging topic [1,2], developed most fully in the field of quantum optics [3]. Only recently have these ideas been extended to quantum transport, a field which looks to understand and control the motion of electrons through structures on the nano-scale [4]. The aim of this contribution is to review these recent developments.Broadly speaking, quantum feedback strategies may usefully be classified into two types:• Measurement-based control, where the quantum system is subject to measurements, the classical information from which forms the basis of the feedback loop; • Coherent control, where the system, the controller and their interconnections are phase coherent such that the information flow in the feedback loop is of quantum information [5].Mirroring the situation in optics, most of the work to-date on feedback in quantum transport has been within the measurement-based paradigm. In Sec. 1.2 here, we discuss a number of different measurement-based schemes

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Principles and applications of quantum control engineering

Cited by 28 publications

References 54 publications

Continuous joint measurement and entanglement of qubits in remote cavities

Continuous joint measurement and entanglement of qubits in remote cavities

Horizons of cybernetical physics

Feedback Control in Quantum Transport

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