Nonreciprocal microwave devices are ubiquitous in radar and radio communication and indispensable in the readout chains of superconducting quantum circuits. Since they commonly rely on ferrite materials requiring large magnetic fields that make them bulky and lossy, there has been significant interest in magnetic-field-free on-chip alternatives, such as those recently implemented using the Josephson nonlinearity. Here, we realize reconfigurable nonreciprocal transmission between two microwave modes using purely optomechanical interactions in a superconducting electromechanical circuit. The scheme relies on the interference in two mechanical modes that mediate coupling between the microwave cavities and requires no magnetic field. We analyse the isolation, transmission and the noise properties of this nonreciprocal circuit. Finally, we show how quantum-limited circulators can be realized with the same principle. All-optomechanically mediated nonreciprocity demonstrated here can also be extended to directional amplifiers, and it forms the basis towards realizing topological states of light and sound.
Directional amplifiers are an important resource in quantum information processing, as they protect sensitive quantum systems from excess noise. Here, we propose an implementation of phase-preserving and phase-sensitive directional amplifiers for microwave signals in an electromechanical setup comprising two microwave cavities and two mechanical resonators. We show that both can reach their respective quantum limits on added noise. In the reverse direction, they emit thermal noise stemming from the mechanical resonators and we discuss how this noise can be suppressed, a crucial aspect for technological applications. The isolation bandwidth in both is of the order of the mechanical linewidth divided by the amplitude gain. We derive the bandwidth and gain-bandwidth product for both and find that the phase-sensitive amplifier has an unlimited gain-bandwidth product. Our study represents an important step toward flexible, on-chip integrated nonreciprocal amplifiers of microwave signals.Introduction.-Nonreciprocal transmission and amplification of signals are essential in communication and signal processing, as they protect the signal source from extraneous noise. Conventional ferrite-based devices rely on magnetic fields and are challenging to integrate in superconducting circuits. Hence, there exists strong incentive to find more suitable implementations [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In the microwave domain, the strong Josephson nonlinearity and parametric pumping can achieve both photon gain and conversion processes, which have been exploited to realize circulators and directional amplifiers [5,[13][14][15]]. Another promising platform is optomechanics, where nonreciprocal devices [16][17][18][19][20][21][22][23][24][25][26][27], phase-preserving amplifiers [28][29][30][31][32], and phase-sensitive amplifiers [33][34][35][36] have been proposed and realized.In recent theoretical work, Ranzani and Aumentado [16,17] analyzed general conditions for nonreciprocity in parametrically coupled systems, and showed that nonreciprocity arises due to dissipation in ancillary modes and multi-path interference. Metelmann and Clerk [18] have shown that any coherent interaction can be made directional by balancing it with a dissipative process. Indeed, this insight led to a demonstration of nonreciprocity using optomechanics in the optical domain [19], and theoretical investigations into minimal implementations of directional amplifiers [20].While implementing the balance between a direct coherent coupling between the cavities and a dissipative interaction is challenging experimentally, Refs. [25][26][27] have recently studied and demonstrated nonreciprocal transmission between two cavity modes where two mechanical resonators each mediate both coherent and dissipative coupling. Here, building on this concept, we propose directional amplifiers using exclusively optomechanical interactions. Microwave tones on the red and blue sidebands enable so-called beam-splitter and two-mode squeezing interactions (cf. Fig. ...
Level repulsion -the opening of a gap between two degenerate modes due to coupling -is ubiquitous anywhere from solid state theory to quantum chemistry. In contrast, if one mode has negative energy, the mode frequencies attract instead. They converge and develop imaginary components, leading to an instability; an exceptional point marks the transition. This, however, only occurs if the dissipation rates of the two modes are comparable. Here we expose a theoretical framework for the general phenomenon and realize it experimentally through engineered dissipation in a multimode superconducting microwave optomechanical circuit. Level attraction is observed for a mechanical oscillator and a superconducting microwave cavity, while an auxiliary cavity is used for sideband cooling. Two exceptional points are demonstrated that could be exploited for their topological properties.arXiv:1709.02220v2 [cond-mat.mes-hall]
We propose a device architecture capable of direct quantum electro-optical conversion of microwave to optical photons. The hybrid system consists of a planar superconducting microwave circuit coupled to an integrated whispering-gallery-mode microresonator made from an electrooptical material. We show that by exploiting the large vacuum electric field of the planar microwave resonator, electro-optical (vacuum) coupling rates g0 as large as ∼ 2π O(10 − 100) kHz are achievable with currently available technology -a more than three order of magnitude improvement over prior designs and realizations. Operating at millikelvin temperatures, such a converter would enable high-efficiency conversion of microwave to optical photons. We analyze the added noise, and show that maximum quantum coherent conversion efficiency is achieved for a multi-photon cooperativity of unity which can be reached with optical power as low as O(1) mW.The interconversion of microwave and optical signals is of practical relevance in a broad range of electronic applications, from optical and wireless communications to timing. The spectacular advances of the past decade in manipulating the quantum states of the microwave field [1, 2] has increased interest in techniques to convert them to optical fields, since the latter can be propagated via optical fiber at room temperature while preserving their quantum state. In the long term, converting quantum states between microwave and optical photons may enable long distance quantum communication [3,4], and in the near term, it provides a path towards realizing single photon detectors of the microwave field that may find use in quantum science and metrology, radio astronomy and technology alike. For these reasons, hybrid systems for such microwave to optical interfaces have recently attracted significant experimental efforts. Several approaches have been investigated [5,6]: optomechanical and electromechanical devices [7][8][9][10] as well as cold atoms [11] and spin ensembles [12,13]. Indeed, a bi-directional and efficient link has been established recently using a mechanical oscillator coupled to both optical and microwave modes. Alternatively, it has been proposed that the parametric coupling of an LC circuit to an optical cavity via an electro-optical crystal would realize an effective optomechanical-type interaction [14]. Such a system could convert states from the microwave to the optical domain by driving sideband cooling transitions [15][16][17]. Similar to optomechanical systems, the interaction requires large vacuum coupling rates and the resolved-sideband regime [15][16][17] to be efficient as well as a optical cavity decay rate that greatly exceeds the microwave decay rate. Despite interest in the scheme, to date, it has not been realized. Previous demonstrations attained vacuum coupling rates of ∼ 2π O(1 − 10)Hz insufficient for an efficient transfer. In addition, several previous schemes operated with a microwave dissipation that was larger than the optical one, preventing efficient transfer...
Isolation of a system from its environment is often desirable, from precision measurements 1 to control of individual quantum systems; however, dissipation can also be a useful resource. Remarkably, engineered dissipation 2 enables the preparation of quantum states of atoms, ions or superconducting qubits 3-8 as well as their stabilization 9 . This is achieved by a suitably engineered coupling to a dissipative cold reservoir formed by electromagnetic modes. Similarly, in the field of cavity electro-and optomechanics 10 , the control over mechanical oscillators utilizes the inherently cold, dissipative nature of the electromagnetic degree of freedom. Breaking from this paradigm, recent theoretical work [11][12][13][14][15] has considered the opposite regime in which the dissipation of the mechanical oscillator dominates and provides a cold dissipative reservoir to an electromagnetic mode. Here we realize this reversed dissipation regime 13 in a microwave cavity optomechanical system 16 and realize a quasi-instantaneous, cold reservoir for microwave light. Coupling to this reservoir enables to manipulate the susceptibility of the microwave cavity, corresponding to dynamical backaction control of the microwave field. Additionally, we observe the onset of parametric instability, i.e. the stimulated emission of microwaves (masing) 17,18 . Equally important, the reservoir can function as a useful quantum resource. We evidence this by employing the engineered cold reservoir to implement a large gain (above 40 dB) phase preserving microwave amplifier that operates 0.87 quanta above the limit of added noise imposed by quantum mechanics (×2 above the device's quantum limit). Beyond offering the manipulation of microwave fields, such a dissipative cold reservoir, when coupled to multiple cavity modes, forms the basis of microwave entanglement schemes 11 , amplifiers with unlimited gain-bandwidth product 12 and the study of dissipative quantum phase transitions 19 . Moreover, combining such reservoir-mediated interaction with coherent dynamics allows for the realization of recently predicted non-reciprocal devices 15 . These devices could operate in the quantum regime when employing a cold reservoir as a quantum resource, thereby extending the available toolbox of quantum-limited microwave manipulation techniques [20][21][22][23][24] .Reservoir engineering defies the notion that dissipation is necessarily detrimental for the utility of a quantum system. In fact, if carefully constructed, dissipation can relax the system of interest to a desired target quantum state, e.g. an entangled state. This pioneering insight was first theoretically conceived and studied in the context of trapped ions 2 , experimentally first realized with trapped atomic ensembles 3 and later with trapped ions 4-6 . Moreover, reservoir engineering has recently also been realized in the context of circuit QED [7][8][9] . In these experiments the optical or microwave field provides a dissipative reservoir to the quantum systems. In cavity optomechanics 1...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.