On-Chip Microwave Quantum Hall Circulator

TL;DR

This paper demonstrates a compact, passive on-chip microwave circulator utilizing the chiral, slow-light response of a quantum Hall 2DEG, achieving significant non-reciprocity and reconfigurability for integrated microwave systems.

Contribution

It introduces a novel on-chip microwave circulator based on quantum Hall effects, significantly reducing size and enabling dynamic circulation direction control.

Findings

Achieved 25 dB non-reciprocity over 50 MHz bandwidth.

Device size is one-thousandth of the wavelength.

Circulation direction can be dynamically controlled by magnetic field.

Abstract

Circulators are non-reciprocal circuit elements integral to technologies including radar systems, microwave communication transceivers, and the readout of quantum information devices. Their non-reciprocity arises from the interference of microwaves over the centimetre-scale of the signal wavelength in the presence of bulky magnetic media that break time-reversal symmetry. Here we realize a completely passive on-chip microwave circulator with size one-thousandth the wavelength by exploiting the chiral, slow-light response of a 2-dimensional electron gas (2DEG) in the quantum Hall regime. For an integrated GaAs device with 330 um diameter and 1 GHz centre frequency, a non-reciprocity of 25 dB is observed over a 50 MHz bandwidth. Furthermore, the direction of circulation can be selected dynamically by varying the magnetic field, an aspect that may enable reconfigurable passive routing of microwave signals on-chip.