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Parametric frequency conversion in two coupled superconducting resonators

Andreas Bengtsson

Published Jan 1, 2015• 0 citations
OpenAlex

Abstract

In this work, we have designed, fabricated, and characterized two coupled superconducting microwave resonators.\n\nUsing this system, we investigate a parametric frequency conversion process in the microwave regime. We modulate the resonance frequency at the difference frequency between two modes, i.e. by three-wave mixing. An incoming signal, resonant with one of the modes, is then converted to the other mode. We demonstrate this behavior in several different schemes, e.g. using one or two modulation tones. We report a conversion efficiency of 50%, meaning that 50% of the incoming wave amplitude gets converted to the other frequency.\n\nFinally, we discuss the possibilities to use such a system in a quantum computing architecture.

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In this work, we have designed, fabricated, and characterized two coupled superconducting microwave resonators.\n\nUsing this system, we investigate a parametric frequency conversion process in the microwave regime. We modulate the resonance frequency at the difference frequency between two modes, i.e. by three-wave mixing. An incoming signal, resonant with one of the modes, is then converted to the other mode. We demonstrate this behavior in several different schemes, e.g. using one or two modulation tones. We report a conversion efficiency of 50%, meaning that 50% of the incoming wave amplitude gets converted to the other frequency.\n\nFinally, we discuss the possibilities to use such a system in a quantum computing architecture.
Parametric frequency converters (PFCs) play a critical role in bridging the frequency gap between quantum information carriers. PFCs in the microwave band are particularly important for superconducting quantum processors, but their operating bandwidth is often strongly limited. Here, we present a multimode kinetic metastructure for parametric frequency conversion between broadly spanning frequency modes. This device comprises a chain of asymmetric kinetic inductance grids designed to deliver efficient three-wave mixing nonlinearity. We demonstrate high efficient coherent conversion among broadly distributed modes, and the mode frequency is continuously tunable by controlling the external magnetic field strength, making it ideally suited for quantum computing and communication applications requiring flexible and efficient frequency conversion.
We study a superconducting circuit that can act as a toolbox to generate various Bogoliubov linear and nonlinear quantum operations on the microwave photon modes of superconducting resonators within one single circuit. The quantum operations are generated by exploring dispersive four-wave mixing (FWM) processes involving the resonator modes. Different FWM geometries can be realized by adjusting the circuit parameters and by applying appropriate microwave drivings. We illustrate this scheme using a circuit made of two superconducting qubits that couple with each other. Each qubit couples with one superconducting resonator. We also discuss main sources of quantum errors in this system and study the fidelity of the quantum operations by numerical simulation. Our scheme provides a practical approach to realize quantum information protocols on superconducting resonators.
The research reported here details experimental progress toward future superconductor-based quantum computing technologies. Specifically, we present techniques for moving quantum information between various cavity resonators -- spatially as well as between frequencies. Rather than using traditional resonant coupling though, we induce non-resonant coupling through parametric frequency conversion. This technology is mediated by chip-based, micro-fabricated, Josephson Junction circuits.\nParametric processes have the advantage over traditional coupling by allowing the constituents of the system -- for example: cavity modes or qubits -- to remain fixed in frequency, tuned to their optimal operation frequency, thereby avoiding unwanted resonant interactions. As the number of constituents grows -- as quantum computing architectures expand to more and more bits -- these techniques will become necessary to optimize performance.\nOutside of the focus on quantum computation, these techniques have wide application for materials research, quantum optics, and extending traditionally optical-frequency experiments to microwave-frequencies. To that end, we demonstrate a hybrid quantum technology which expands the toolbox of superconducting quantum information to a new system, namely sapphire whispering gallery mode resonators. These resonators have been studied in the optical frequency domain, but here we demonstrate their usefulness at microwave frequencies.\nAll of the experiments in this dissertation should be considered proof-of-principle demonstrations of a future technology. Thus, we note when and where improvements for future devices will be necessary.
Abstract We propose an efficient scheme for microwave-to-optical quantum frequency conversion mediated by a single atom simultaneously coupled to a superconducting microwave resonator and an optical cavity. The atom mediates efficient interactions between the two electromagnetic modes via non-linear frequency mixing owing to the presence of huge microwave transition dipole moments between nearby Rydberg states as well as suitable optical transitions between low-lying states. In the regime of four-wave mixing with off-resonant fields, the excited states can be adiabatically eliminated, leading to an effective Hamiltonian that directly describes the two-mode interaction responsible for the frequency conversion. However, in this regime, the converter is slow, hence sensitive to losses due to cavity decays. To enhance the performance of the conversion process, we employ pulse engineering to tailor the atom-field couplings. The resulting protocol exhibits high robustness against decoherence and parameter fluctuations, making it well suited for realistic experimental implementations. Our scheme provides a promising route toward high-fidelity and scalable hybrid quantum interfaces connecting superconducting and optical quantum networks.
We experimentally demonstrate a coupled superconducting resonator system in which a superconducting quantum interference device (SQUID) modulated nonlinear resonator is capacitively coupled to a fixed-frequency linear resonator. This configuration enables flux-tunable mode separation and parametric interactions between spatially separated modes. By exploiting the SQUID-induced nonlinearity, we achieve both single-mode (degenerate) and two-mode (nondegenerate) parametric amplification via three-wave mixing processes. Gains exceeding 15 dB are obtained in both the tunable resonator and the fixed frequency linear resonator with near quantum limit noise performance. Our device may provide an attractive solution for storing and releasing squeezed photons.