Passive On-Chip Superconducting Circulator Using a Ring of Tunnel Junctions

Abstract

We present the design of a passive, on-chip microwave circulator based on a ring of superconducting tunnel junctions. We investigate two distinct physical realizations, based on Josephson junctions (JJs) or quantum phase slip elements (QPS), with microwave ports coupled either capacitively (JJ) or inductively (QPS) to the ring structure. A constant bias applied to the center of the ring provides an effective symmetry breaking field, and no microwave or rf bias is required. We show that this design offers high isolation, robustness against fabrication imperfections and bias fluctuations, and a bandwidth in excess of 500 MHz for realistic device parameters.

Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum

“…We extract QP relaxation times in the range of 1 s and we observe QP bursts every ∼20 s. The current level of coherence of grAl resonators makes them attractive for integration in quantum devices, while it also evidences the need to reduce the density of nonequilibrium QPs. DOI: 10.1103/PhysRevLett.121.117001 Superconducting materials with a high kinetic inductance play a prominent role in superconducting circuits, such as quantum bits (qubits) with remarkably high energy relaxation times [1][2][3][4], topological [5,6] and protected qubits [7][8][9], coherent quantum phase slip circuits [10][11][12][13], wideband parametric amplifiers [14,15], and resonators for quantum state of light engineering [16,17]. As the kinetic inductance fraction α ¼ L kinetic =L total increases, so does the susceptibility of superconducting circuits to quasiparticle (QP) excitations, which constitutes an asset for kinetic inductance detectors (KIDs) [18].…”

Nonreciprocity Realized with Quantum Nonlinearity

“…Different approaches to achieve nonreciprocity on a chip are being actively pursued to enable circuits of greater complexity and advanced functionality. A common path to achieve nonreciprocity consists in breaking time-reversal symmetry, either by utilizing novel materials [2][3][4] or by exploiting sophisticated time control schemes [5][6][7][8][9][10]. Here, we follow another path and use a pair of tunable superconducting artificial atoms in a 1D waveguide in order to realize the simplest possible nonreciprocal device without breaking time-reversal symmetry.…”

Transmission Lines and Metamaterials Based on Quantum Hall Plasmonics

“…Considering that v 1,2,B ∝ 1/c 1,2,B , one can obtain Eq. (25). Also, the presence of two capacitors in the driving regions immediately explains the partition of voltages and currents: only a factor c −1 B /(c −1 1,2 +c −1 B ) = 1−ṽ 1,2 /v B of the total applied voltage and of the total current is relevant for the response.…”

“…The chirality of these devices, for example, can be exploited to implement minaturized, scalable non-reciprocal devices such as gyrators and circulators [7,[22][23][24] that are broadly used for manipulation of qubits and back-action mitigation. Other passive implementations are also possible [25].…”