Long-distance entanglement of spin qubits via quantum Hall edge states

Yang, Guang; Hsu, Chia-Hsiang; Stano, Peter; Klinovaja, Jelena; Loss, Daniel

doi:10.1103/physrevb.93.075301

Cited by 28 publications

(22 citation statements)

References 52 publications

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“…Since the exchange interaction is limited to adjacent QDs, other long-range interactions have to be considered to overcome this technical difficulty allowing for a two-dimensional array of qubits which are spatially separated [236]. There are several proposals for the achievement of such an interaction, e.g., tunneling mediated by a superconductor [237,238], coupling though surface acoustic waves [239,240,241,242,243,244], ferromagnets [245], superexchange mediated by an additional QD [246,247,92,248], spatial adiabatic passage [249,222,250], photon assisted tunneling [251,252,253], and quantum Hall edge states [254,243]. The most practical ideas (up to date) seem to be Coulomb-based dipoledipole coupling [10,255,256] and cavity quantum electrodynamics (cQED) mediated coupling [137,16,187,211,105,17,257,258,106] which both use the electric dipole moment of the qubit, whereas in the second approach the interaction range is elongated by the use of a cavity as a mediator [97,98,16,17,3].…”

Section: Long-ranged Two-qubit Gatesmentioning

confidence: 99%

Three-electron spin qubits

Russ

Burkard

2017

J. Phys.: Condens. Matter

104

117

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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 exchange-only qubit (Bacon et al 2000 Phys. Rev. Lett. 85 1758-61, DiVincenzo et al 2000 Nature 408 339) and its derived versions, e.g. the resonant exchange (RX) qubit, but we also discuss other qubit implementations using three electron spins. For each three-spin qubit we describe the qubit model, the envisioned 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 quantum computation for a viable candidate qubit implementation. We start by describing the full system of three electrons in a triple quantum dot, then discuss the charge-stability diagram, restricting ourselves to the relevant subsystem, introduce the qubit states, and discuss important transitions to other charge states (Russ et al 2016 Phys. Rev. B 94 165411). Introducing the various qubit implementations, we begin with the exchange-only qubit (DiVincenzo et al 2000 Nature 408 339, Laird et al 2010 Phys. Rev. B 82 075403), followed by the RX qubit (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502), the spin-charge qubit (Kyriakidis and Burkard 2007 Phys. Rev. B 75 115324), and the hybrid qubit (Shi et al 2012 Phys. Rev. Lett. 108 140503, Koh et al 2012 Phys. Rev. Lett. 109 250503, Cao et al 2016 Phys. Rev. Lett. 116 086801, Thorgrimsson et al 2016 arXiv:1611.04945). The main focus will be on 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. Two different types of two-qubit operations are presented for the exchange-only qubits which can be divided into short-ranged and long-ranged interactions. Both of these interaction types are expected to be necessary in a large-scale quantum computer. The short-ranged interactions use the exchange coupling by placing qubits next to each other and applying exchange-pulses (DiVincenzo et al 2000 Nature 408 339, Fong and Wandzura 2011 Quantum Inf. Comput. 11 1003, Setiawan et al 2014 Phys. Rev. B 89 085314, Zeuch et al 2014 Phys. Rev. B 90 045306, Doherty and Wardrop 2013 Phys. Rev. Lett. 111 050503, Shim and Tahan 2016 Phys. Rev. B 93 121410), while the long-ranged interactions use the photons of a superconducting microwave cavity as a mediator in order to couple two qubits over long distances (Russ and Burkard 2015 Phys. Rev. B 92 205412, Srinivasa et al 2016 Phys. Rev. B 94 205421). The nature of the three-electron qubit states each having the same total spin and total spin in z-direction (same Zeeman energy) provides a natural protection against several sources of noise (DiVincenzo et al 2000 Nature 408 339, Taylor et al 2013 Phys. R...

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Section: Long-ranged Two-qubit Gatesmentioning

confidence: 99%

Three-electron spin qubits

Russ

Burkard

2017

J. Phys.: Condens. Matter

104

117

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“…This scheme differs from Ref. 35, where the main process of coupling qubits to the edge is through the exchange interaction.…”

Section: Electrostatic Qubit-edge Mode Couplingmentioning

confidence: 94%

Long-range entanglement for spin qubits via quantum Hall edge modes

2017

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We propose and analyse a scheme for performing a long-range entangling gate for qubits encoded in electron spins trapped in semiconductor quantum dots. Our coupling makes use of an electrostatic interaction between the state-dependent charge configurations of a singlet-triplet qubit and the edge modes of a quantum Hall droplet. We show that distant singlet-triplet qubits can be selectively coupled, with gate times that can be much shorter than qubit dephasing times and faster than decoherence due to coupling to the edge modes. Based on parameters from recent experiments, we argue that fidelities above 99% could in principle be achieved for a two-qubit entangling gate taking as little as 20 ns.

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“…Coherent control via a mesoscopic system is an emerging tool in quantum information processing [1][2][3][4][5][6][7][8]. Using a mesoscopic system to indirectly measure a joint property of two noninteracting qubits through a coarse-grained collective measurement has recently been introduced as a new approach for entangling uncoupled qubits [9].…”

Section: Introductionmentioning

confidence: 99%

Mesoscopic spin systems as quantum entanglers

Mirkamali

Cory²

2020

Phys. Rev. A

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We quantify the resources required for entangling two uncoupled spin qubits through an intermediate mesoscopic spin system (MSS) by indirect joint measurement. Indirect joint measurement benefits from coherent magnification of the target qubits' state in the collective magnetization of the MSS; such that a low-resolution collective measurement on the MSS suffices to prepare post-selected entanglement on the target qubits. A MSS consisting of two non-interacting halves, each coupled to one of the target qubits is identified as a geometry that allows implementing the magnification process with experimentally available control tools. It is proved that the requirements on the amplified state of the target qubits and the MSS perfectly map to the specifications of micro-macro entanglement between each target qubit and its nearby half of the MSS. In the light of this equivalence, the effects of experimental imperfections are explored; in particular, bipartite entanglement between the target qubits is shown to be robust to imperfect preparation of the MSS. Our study provides a new approach for using an intermediate spin system for connecting separated qubits. It also opens a new path in exploring entanglement between microscopic and mesoscopic spin systems.PACS numbers:

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Long-distance entanglement of spin qubits via quantum Hall edge states

Cited by 28 publications

References 52 publications

Three-electron spin qubits

Three-electron spin qubits

Long-range entanglement for spin qubits via quantum Hall edge modes

Mesoscopic spin systems as quantum entanglers

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