Low-Loss Ferrite Circulator as a Tunable Chiral Quantum System

Wang, Yingying; Geldern, Sean van; Connolly, T.; Wang, Yuxin; Shilcusky, Alexander; McDonald, A. H.; Clerk, Aashish A.; Wang, Chen

doi:10.1103/physrevapplied.16.064066

Cited by 10 publications

(7 citation statements)

References 54 publications

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“…The level of directionality can be tuned in situ via the external field. At an external bias of about ±20 mT, the ferrite-loaded Y-junction functions like a circulator that mediates directional microwave transmission between the cavity side and the transmon side with a bandwidth of a few hundred megahertz ( 26 ).…”

Section: Resultsmentioning

confidence: 99%

“…The collective spin precession inside the YIG crystal (magnon excitations) is hybridized with the electromagnetic modes in the vicinity of the waveguide Y-junction in a chirality-dependent manner, forming a series of chiral photon-magnon polariton modes ( 26 , 27 , 52 ). In particular, a pair of near-degenerate polariton modes with zero-field frequency close to 10.8 GHz are primarily responsible for generating an effective dissipative linear coupling between the cavity and the buffer mode.…”

Section: Methodsmentioning

confidence: 99%

“…The three sides of the Y-junction are connected, respectively, to (i) a narrow-band niobium superconducting cavity (the cavity of interest), which also contains an ancilla transmon for the convenience of cavity state preparation and analysis, (ii) a broadband niobium cavity which functions as a buffer mode and contains the transmon qubit (the qubit of interest), and (iii) a 50-ohm transmission line which is the source of the collective dissipation of the intermediary modes. The collective spin precession inside the YIG crystal (magnon excitations) is hybridized with the electromagnetic modes in the vicinity of the waveguide Y-junction in a chirality-dependent manner, forming a series of chiral photon-magnon polariton modes (26,27,52). In particular, a pair of near-degenerate polariton modes with zero-field frequency close to 10.8 GHz are primarily responsible for generating an effective dissipative linear coupling between the cavity and the buffer mode.…”

Section: Device Detailsmentioning

confidence: 99%

“…In this work, we experimentally realize and characterize a dispersive type of quantum nonreciprocal interaction between a superconducting cavity and a transmon qubit. To access varying degrees of nonreciprocity in situ, we implement a hybrid quantum system where the qubit-cavity interaction is mediated by a complex set of cavitymagnon modes constructed from three-dimensional niobium and copper waveguide cavities and a ferrimagnetic yttrium iron garnet (YIG) crystal (26)(27)(28)(29). We study the nonreciprocal influence between the qubit and the cavity in terms of asymmetric dispersive frequency 1 department of Physics, University of Massachusetts-Amherst, Amherst, MA, USA.…”

Section: Introductionmentioning

confidence: 99%

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Dispersive nonreciprocity between a qubit and a cavity

Wang,

van Geldern

et al. 2024

Sci. Adv.

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The dispersive interaction between a qubit and a cavity is ubiquitous in circuit and cavity quantum electrodynamics. It describes the frequency shift of one quantum mode in response to excitations in the other and, in closed systems, is necessarily bidirectional, i.e., reciprocal. Here, we present an experimental study of a nonreciprocal dispersive-type interaction between a transmon qubit and a superconducting cavity, arising from a common coupling to dissipative intermediary modes with broken time reversal symmetry. We characterize the qubit-cavity dynamics, including asymmetric frequency pulls and photon shot noise dephasing, under varying degrees of nonreciprocity by tuning the magnetic field bias of a ferrite component in situ. We introduce a general master equation model for nonreciprocal interactions in the dispersive regime, providing a compact description of the observed qubit-cavity dynamics agnostic to the intermediary system. Our result provides an example of quantum nonreciprocal phenomena beyond the typical paradigms of non-Hermitian Hamiltonians and cascaded systems.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Device Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dispersive nonreciprocity between a qubit and a cavity

Wang,

van Geldern

et al. 2024

Sci. Adv.

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“…In these studies, a coherent coupling between photons in an electromagnetic cavity and magnons in a ferromagnet is achieved in the strong [5,6], ultrastrong [7][8][9] and, even, close to the deep-strong regimes, [10]. This has opened the way to the observation of interesting phenomena with strong potential for applications like quantum transduction between optical and microwave photons [11,12], dispersive coupling between quantum systems [13][14][15], or nonreciprocal transmission of rf signals [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Measuring the Magnon-Photon Coupling in Shaped Ferromagnets: Tuning of the Resonance Frequency

et al. 2023

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Cavity photons and ferromagnetic spin excitations can exchange information coherently in hybrid architectures, at speeds set by their mutual coupling strength. Speed enhancement is usually achieved by optimizing the geometry of the electromagnetic cavity. Here we show that the geometry of the ferromagnet also plays a role, by setting the fundamental frequency of the magnonic resonator. Using focused ion-beam patterning, we vary the aspect ratio of different Permalloy samples reaching operation frequencies above 10 GHz while working at low external magnetic fields. Additionally, we perform broadband ferromagnetic resonance measurements and cavity experiments that demonstrate that the light-matter coupling strength can be estimated using either open transmission lines or resonant cavities, yielding very good agreement. Finally, we describe a simple theoretical framework based on electromagnetic and micromagnetic simulations that successfully accounts for the experimental results. This approach can be used to design hybrid quantum systems exploiting magnetostatic mode excited in ferromagnets of arbitrary size and shape and to tune their operation conditions.

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