Coherent Coupling of Remote Spin Ensembles via a Cavity Bus

Astner, Thomas; Nevlacsil, Stefan; Peterschofsky, N.; Angerer, Andreas; Rotter, Stefan; Putz, Stefan; Schmiedmayer, Jörg; Majer, Johannes

doi:10.1103/physrevlett.118.140502

Cited by 68 publications

(56 citation statements)

References 34 publications

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“…Regarding experimental implementations, while we have considered here a hybrid superconducting circuit with the ensembles of spins in diamond crystal coupled to the transmission line resonators (forming the Dicke model) [59][60][61][62][63][64], our proposal is not limited to this particular architecture and could be implemented or adapted in a variety of platforms, e.g., atomic [65,66], molecular [67], and ferromagnetic [68][69][70][71] systems coupled to superconducting cavities. For our specific design, considering an ensemble with N ∼ 10 12 spins and the single spin coupling λ 0 ∼ 10 Hz, an enhanced collective coupling λ ≈ √ Nλ 0 ∼ 10 MHz [59][60][61][62][63][64] allows our model to reach an ultrastrong-coupling regime, which demonstrates that the critical coupling of QPT can be readily realized with state-of-the-art technology. To experimentally detect the band structure, one of the most generally used techniques is photoluminescence [24,25].…”

Section: Discussionmentioning

confidence: 99%

Interplay of quantum phase transition and flat band in hybrid lattices

Zhu

Ramezani

Emary

et al. 2020

Phys. Rev. Research

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We establish a connection between quantum phase transitions (QPTs) and energy band theory in an extended Dicke-Hubbard lattice, where the periodical critical curves modulated by wave number k leads to rich equilibrium dynamics. Interestingly, the chiral-symmetry-protected flat band and the localization that it engenders exclusively occurs in the normal phase and disappears in the superradiant phase. This originates from the QPT induced simultaneous breaking up of the on-site resonance condition and off-site chiral symmetry of the system, which prohibits the destructive interference for obtaining a flat band. Our work offers an approach to identify different phases of the lattice via detecting the flat bands or simply the related localizations in a single cell, and, in turn, to control the appearance of flat bands by QPT.

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Section: Discussionmentioning

confidence: 99%

Interplay of quantum phase transition and flat band in hybrid lattices

Zhu

Ramezani

Emary

et al. 2020

Phys. Rev. Research

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“…Qualitatively, the high permeability Co micromagnet concentrates the magnetic field lines, leading to a maximum total field when B ext is aligned with the long axis of the micromagnet. A similar approach was adopted to remotely couple two ensembles of nitrogen vacancy centers in diamond, where the crystal axes of the two diamond samples were rotated relative to one another [31]. We show now that this approach is well-suited for coupling two single spins in silicon via a cavity mode.…”

mentioning

confidence: 96%

Resonant microwave-mediated interactions between distant electron spins

Borjans¹,

Croot²,

Mi³

et al. 2019

Nature

210

174

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Entangling gates for electron spins in semiconductor quantum dots are generally based on exchange, a shortranged interaction that requires wavefunction overlap. Coherent spin-photon coupling raises the prospect of using photons as long-distance interconnects for spin qubits. Realizing a key milestone for spin-based quantum information processing, we demonstrate microwave-mediated spin-spin interactions between two electrons that are physically separated by more than 4 mm. Coherent spin-photon coupling is demonstrated for each individual spin using microwave transmission spectroscopy. An enhanced vacuum Rabi splitting is observed when both spins are tuned into resonance with the cavity, indicative of a coherent spin-spin interaction. Our results demonstrate that microwave-frequency photons can be used as a resource to generate long-range two-qubit gates between spatially separated spins.

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“…As an example, we now consider a hybrid quantum system [57][58][59], where a superconducting transmission line (STL), terminated by a superconducting quantum interference device (SQUID), is magnetically coupled to an NV spin ensemble in diamond (see Appendix D for details). The coherent coupling of an STL cavity to an NV spin ensemble has already been widely implemented in experiments [60][61][62][63][64][65][66]. In particular, the studies by Kubo et al [60,62,63] used a SQUID to control the cavity frequency.…”

Section: Proposed Experimental Implementationmentioning

confidence: 99%

Strong spin squeezing induced by weak squeezing of light inside a cavity

et al. 2020

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We propose a simple method for generating spin squeezing of atomic ensembles in a Floquet cavity subject to a weak, detuned two-photon driving. We demonstrate that the weak squeezing of light inside the cavity can, counterintuitively, induce strong spin squeezing. This is achieved by exploiting the anti-Stokes scattering process of a photon pair interacting with an atom. Specifically, one photon of the photon pair is scattered into the cavity resonance by absorbing partially the energy of the other photon whose remaining energy excites the atom. The scattering, combined with a Floquet sideband, provides an alternative mechanism to implement Heisenberg-limited spin squeezing. Our proposal does not need multiple classical and cavity-photon drivings applied to atoms in ensembles, and therefore its experimental feasibility is greatly improved compared to other cavity-based schemes. As an example, we demonstrate a possible implementation with a superconducting resonator coupled to a nitrogen-vacancy electronic-spin ensemble.

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Coherent Coupling of Remote Spin Ensembles via a Cavity Bus

Cited by 68 publications

References 34 publications

Interplay of quantum phase transition and flat band in hybrid lattices

Interplay of quantum phase transition and flat band in hybrid lattices

Resonant microwave-mediated interactions between distant electron spins

Strong spin squeezing induced by weak squeezing of light inside a cavity

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