Vacuum Rabi Splitting in a Semiconductor Circuit QED System

Toida, Hiraku; Nakajima, Takashi; Komiyama, S.

doi:10.1103/physrevlett.110.066802

Cited by 108 publications

(148 citation statements)

References 26 publications

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“…The lowest dephasing rate in our graphene DQDs represents a lower bound of the dephasing rate, caused by charge fluctuations in the environment. The dephasing rate of 0.3 GHz is comparable to that in GaAs [5,6] and carbon nanotube [4] DQDs. Because the dephasing rate in grapheme DQDs has not been obtained by any other means namely photon-assisted tunneling (PAT), a traditional method, we now speculate here a possible reason.…”

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confidence: 71%

“…The phase shifts at two other γ 2 values ±0.05 GHz away from the optimal value are clearly different from that at the optimal value, which demonstrates the sensitivity of this parameter extraction method. This method has also been extensively used in other studies of the circuit QED of GaAs [5,6], InAs nanowire [7] and carbon nano-tube [2] DQDs. We systematically extracted γ 2 for different charging states, observing dephasing rates over the range 0.3 GHz to 10 GHz [see Fig.…”

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confidence: 99%

“…For example, many experimental studies have recently been performed to study the interaction between quantum dots (QDs) and resonators, in gate-defined carbon-nanotubes [2-4], GaAs [5,6] and InAs nanowire [7,8] structures. Such studies are motivated by considering QDs as promising candidates for quantum information processing.…”

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Charge Number Dependence of the Dephasing Rates of a Graphene Double Quantum Dot in a Circuit QED Architecture

et al. 2015

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We use an on-chip superconducting resonator as a sensitive meter to probe the properties of graphene double quantum dots (DQDs) at microwave frequencies. Specifically, we investigate the charge dephasing rates in a circuit quantum electrodynamics (cQED) architecture. The dephasing rates strongly depend on the number of charges in the dots, and the variation has a period of four charges, over an extended range of charge numbers. Although the exact mechanism of this four-fold periodicity in dephasing rates is an open problem, our observations hint at the four-fold degeneracy expected in graphene from its spin and valley degrees of freedom.In recent years, on-chip microwave resonators have emerged as a useful tool both for coupling distant qubits and for sensitive metrology [1]. For example, many experimental studies have recently been performed to study the interaction between quantum dots (QDs) and resonators, in gate-defined carbon-nanotubes [2-4], GaAs [5,6] and InAs nanowire [7,8] structures. Such studies are motivated by considering QDs as promising candidates for quantum information processing. Graphene has also attracted considerable attention in recent years because of its interesting physical properties and potential applications [9]. Like semiconductors, graphene-based QDs have been proposed as potential quantum bits [10]. Various experiments are now underway to study the coherence properties of graphene QDs. For example, using pulsed-gate transient spectroscopy, Volk et al.[11] measured a charge relaxation time of 100 ns in a graphene QD device. However, the dephasing times of grapheme QDs, which benchmark their quantum coherence and may be significantly shorter than their relaxation times, have not yet been measured. In addition, graphene has both spin and valley degrees of freedom, similar to carbon nanotubes [12,13] and Si-based QDs [14]. Spin qubits formed by graphene QDs have been theoretically studied [10], and various valley-related phenomena such as shell filling in carbon nanotubes [12] and valley splitting in silicon [15] have been explored. However, there are no experimental reports on the effects of the four-fold degeneracy caused by the spin and valley degrees in graphene devices.Here, we present an experimental study of a graphene DQD device, which can be considered as a charge qubit that contains a large number of well-defined charge * Corresponding author: gpguo@ustc.edu.cn states. Using the sensitive dispersive readout of a microwave resonator, we measured the charge-state dephasing rates of this DQD in an integrated grapheneresonator device. Applying a quantum model describing the hybrid system, we simultaneously extracted: the DQD-resonator coupling strength, the tunneling rate between each quantum dot, and the charge-state dephasing rates. This microwave spectroscopy overcomes the difficulties of conventional transport techniques and allows us to study DQD dynamics in a large parameter space. In these experiments, we found that the dephasing rates depend on the number of charges in t...

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Charge Number Dependence of the Dephasing Rates of a Graphene Double Quantum Dot in a Circuit QED Architecture

et al. 2015

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“…figure 18. Such hybrid structures that allow the investigation the interplay of light and matter at the nansocale have recently gained a lot of interest both theoretically [167,168,169,170,171,172,173,174,175,176,177] as well as experimentally [178,179,180,181,182,183,184,185,186] in the context of circuit quantum electrodynamics. Similar to the previously discussed energy harvester, the hybrid microwave cavity heat engine [57] also allows to separate the hot and the cold part of the engine by a macroscopic distance of the order of a centimeter.…”

Section: Microwave Cavity Photonsmentioning

confidence: 99%

Thermoelectric energy harvesting with quantum dots

2014

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Abstract. We review recent theoretical work on thermoelectric energy harvesting in multi-terminal quantum-dot setups. We first discuss several examples of nanoscale heat engines based on Coulomb-coupled conductors. In particular, we focus on quantum dots in the Coulomb-blockade regime, chaotic cavities and resonant tunneling through quantum dots and wells. We then turn towards quantum-dot heat engines that are driven by bosonic degrees of freedom such as phonons, magnons and microwave photons. These systems provide interesting connections to spin caloritronics and circuit quantum electrodynamics.

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“…In cQED systems with superconducting qubits, cavity photons are also widely used for dispersive state readout, as the significant electric dipole moments of these devices result in large phase shifts in the cavity response. 13,14 In semiconductor systems, hybrid cQED devices have been implemented using GaAs, 15,16 InAs, 17 carbon nanotube, 18 and graphene QDs. 19 There are several proposals pertaining to the coupling of Si spin qubits to cavities, 20,21 as well as the demonstration of a high kinetic inductance cavity, fabricated with the intention of coupling to Si quantum dots.…”

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confidence: 99%

Circuit quantum electrodynamics architecture for gate-defined quantum dots in silicon

Cady

Zajac

et al. 2017

Applied Physics Letters

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We demonstrate a hybrid device architecture where the charge states in a double quantum dot (DQD) formed in a Si/SiGe heterostructure are read out using an on-chip superconducting microwave cavity. A quality factor Q = 5,400 is achieved by selectively etching away regions of the quantum well and by reducing photon losses through low-pass filtering of the gate bias lines. Homodyne measurements of the cavity transmission reveal DQD charge stability diagrams and a charge-cavity coupling rate g c /2π = 23 MHz. These measurements indicate that electrons trapped in a Si DQD can be effectively coupled to microwave photons, potentially enabling coherent electron-photon interactions in silicon.

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Vacuum Rabi Splitting in a Semiconductor Circuit QED System

Cited by 108 publications

References 26 publications

Charge Number Dependence of the Dephasing Rates of a Graphene Double Quantum Dot in a Circuit QED Architecture

Charge Number Dependence of the Dephasing Rates of a Graphene Double Quantum Dot in a Circuit QED Architecture

Thermoelectric energy harvesting with quantum dots

Circuit quantum electrodynamics architecture for gate-defined quantum dots in silicon

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