scispace - formally typeset
Search or ask a question
Author

Bao-Chuan Wang

Bio: Bao-Chuan Wang is an academic researcher from University of Science and Technology of China. The author has contributed to research in topics: Qubit & Quantum dot. The author has an hindex of 6, co-authored 15 publications receiving 184 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: This work shows a new way to encode a semiconductor qubit that is controllable and coherent and leads to quasiparallel energy levels and a new anticrossing, which help preserve quantum coherence of the qubit and yield a useful working point.
Abstract: We experimentally demonstrate a tunable hybrid qubit in a five-electron GaAs double quantum dot. The qubit is encoded in the (1,4) charge regime of the double dot and can be manipulated completely electrically. More importantly, dot anharmonicity leads to quasiparallel energy levels and a new anticrossing, which help preserve quantum coherence of the qubit and yield a useful working point. We have performed Larmor precession and Ramsey fringe experiments near the new working point and find that the qubit decoherence time is significantly improved over a charge qubit. This work shows a new way to encode a semiconductor qubit that is controllable and coherent.

93 citations

Journal ArticleDOI
TL;DR: In this article, a hybrid charge-spin qubit in a linear triple quantum dot with asymmetric tunnel couplings, in a multielectron charge configuration, has been realized for quantum computing based on semiconductor quantum dots.
Abstract: In quantum computing based on semiconductor quantum dots, adding dots (or just electrons) allows a wider search for an optimal qubit-encoding scheme that is both controllable and coherent. This work reports experiments to realize a hybrid charge-spin qubit in a linear triple quantum dot with asymmetric tunnel couplings, in a multielectron charge configuration. This qubit's energy splitting can be tuned conveniently over a wide range, and the authors attain qualitative understanding of the observations in terms of a three-electron system. This should stimulate further exploration of quantum coherent dynamics in the few-electron regime for semiconductor quantum processors.

32 citations

Journal ArticleDOI
TL;DR: In this article, the authors have observed spin blockade near the (1,2)-(2,1) charge transition using a pulsed-gate technique and a charge sensor, and used this spin blockade to detect Landau-Zener-Stuckelberg interference and coherent oscillations between spin quadruplet and doublet states.
Abstract: Asymmetry in a three-electron double quantum dot (DQD) allows spin blockade, when spin-3/2 (quadruplet) states and spin-1/2 (doublet) states have different charge configurations. We have observed this DQD spin blockade near the (1,2)-(2,1) charge transition using a pulsed-gate technique and a charge sensor. We, then, use this spin blockade to detect Landau-Zener-St\"uckelberg interference and coherent oscillations between the spin quadruplet and doublet states. Such studies add to our understandings of coherence and control properties of three-spin states in a double dot, which, in turn, would benefit explorations into various qubit encoding schemes in semiconductor nanostructures.

27 citations

Journal ArticleDOI
TL;DR: In this article, the authors experimentally demonstrate quantum coherent dynamics of a triple-dot-based multi-electron hybrid qubit and compare it with double-dot hybrid qubits.
Abstract: We experimentally demonstrate quantum coherent dynamics of a triple-dot-based multi-electron hybrid qubit. Pulsed experiments show that this system can be conveniently initialized, controlled, and measured electrically, and has good coherence time as compared to gate time. Furthermore, the current multi-electron hybrid qubit has an operation frequency that is tunable in a wide range, from 2 to about 15 GHz. We provide qualitative understandings of the experimental observations by mapping it onto a three-electron system, and compare it with the double dot hybrid qubit and the all-exchange triple-dot qubit.

23 citations

Journal ArticleDOI
TL;DR: In this article, the coupling of two microwave-photon-coupled semiconductor qubits via a high-impedance resonator is characterized using a spectroscopic method.
Abstract: We develop a new spectroscopic method to quickly and intuitively characterize the coupling of two microwave-photon-coupled semiconductor qubits via a high-impedance resonator. Highly distinctive and unique geometric patterns are revealed as we tune the qubit tunnel couplings relative to the frequency of the mediating photons. These patterns are in excellent agreement with a simulation using the Tavis-Cummings model, and allow us to readily identify different parameter regimes for both qubits in the detuning space. This method could potentially be an important component in the overall spectroscopic toolbox for quickly characterizing certain collective properties of multiple cavity QED coupled qubits.

21 citations


Cited by
More filters
Book
01 Jan 2010

1,870 citations

DOI
20 Dec 2012

170 citations

Journal ArticleDOI
TL;DR: In this paper, the basic ideas for quantum computing, and then discuss the developments of single and two-qubit gate control in semiconductors are discussed, considering the positive trend of the research on semiconductor quantum devices and recent theoretical work on the applications of quantum computation.
Abstract: Semiconductors, a significant type of material in the information era, are becoming more and more powerful in the field of quantum information. In recent decades, semiconductor quantum computation was investigated thoroughly across the world and developed with a dramatically fast speed. The research varied from initialization, control and readout of qubits, to the architecture of fault-tolerant quantum computing. Here, we first introduce the basic ideas for quantum computing, and then discuss the developments of single- and two-qubit gate control in semiconductors. Up to now, the qubit initialization, control and readout can be realized with relatively high fidelity and a programmable two-qubit quantum processor has even been demonstrated. However, to further improve the qubit quality and scale it up, there are still some challenges to resolve such as the improvement of the readout method, material development and scalable designs. We discuss these issues and introduce the forefronts of progress. Finally, considering the positive trend of the research on semiconductor quantum devices and recent theoretical work on the applications of quantum computation, we anticipate that semiconductor quantum computation may develop fast and will have a huge impact on our lives in the near future.

105 citations

Journal Article
TL;DR: In this article, a coherent microwave source that is driven by the tunneling of single electrons in semiconductor double-quantum dots is demonstrated, and the authors verify maser action by comparing the statistics of the emitted microwave field above and below the maser threshold.
Abstract: Tunnel through and emit coherently The generation of coherent light (lasers and masers) forms the basis of a large optics industry. Liu et al. demonstrate a type of laser that is driven by the tunneling of single electrons in semiconductor double-quantum dots. Distinct from other existing semiconductor lasers, the emission mechanism is driven by tunneling of single charges between discrete energy levels that are electrically tunable. The ability to tune the levels by single-electron charging would allow their laser (or maser) to be turned on and off rapidly. Science, this issue p. 285 A coherent microwave source that is driven by the tunneling of single electrons is demonstrated. The coherent generation of light, from masers to lasers, relies upon the specific structure of the individual emitters that lead to gain. Devices operating as lasers in the few-emitter limit provide opportunities for understanding quantum coherent phenomena, from terahertz sources to quantum communication. Here we demonstrate a maser that is driven by single-electron tunneling events. Semiconductor double quantum dots (DQDs) serve as a gain medium and are placed inside a high-quality factor microwave cavity. We verify maser action by comparing the statistics of the emitted microwave field above and below the maser threshold.

83 citations

Journal ArticleDOI
TL;DR: The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art, with the main focus towards the exchange-only qubit and its modification, the RX qubit, whose single-qubit operations are realized by driving the qubit at its resonant frequency in the microwave range similar to electron spin resonance.
Abstract: The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art. We direct the main focus towards the resonant exchange (RX) qubit and the exchange-only qubit, but we also discuss other qubit implementations using three electron spins. For each three-spin qubit we describe the qubit model, the physical realization, the implementations of single-qubit operations, as well as the read-out and initialization schemes. Two-qubit gates and decoherence properties are discussed for the RX qubit and the exchange-only qubit, thereby, completing the list of requirements for a viable candidate qubit implementation for quantum computation. We start with describing the full system of three electrons in a triple quantum dot, then discuss the charge-stability diagram and restrict ourselves to the relevant subsystem, introduce the qubit states, and discuss important transitions to other charge states. Introducing the various qubit implementations, we begin with the exchange-only qubit, followed by the spin-charge qubit, the hybrid qubit, and the RX qubit, discussing for each the single-qubit operations, read-out, and initialization methods, whereas the main focus will be on the RX qubit, whose single-qubit operations are realized by driving the qubit at its resonant frequency in the microwave range similar to electron spin resonance. Two different types of two-qubit operations are presented for the exchange-only and the RX qubit which can be divided into short-ranged and long-ranged interactions. Both of these interaction types can be expected to be necessary in a large-scale quantum computer. We also take into account the decoherence of the qubit through the influence of magnetic noise as well as dephasing due to charge noise.

83 citations