Microwave absorption by a mesoscopic quantum Hall droplet

Abstract

We consider the absorption of microwaves by a quantum Hall droplet. We show that the number and velocities of charged edge modes can be directly measured from a droplet of known shape. In contrast to standard transport measurements, different edge equilibration regimes can be accessed in the same device. If there is a quantum point contact in the droplet, then quasiparticle properties, including braiding statistics, can be observed. Their effects are manifested as modulations of the microwave absorption spectrum that are, notably, first-order in the tunneling amplitude at the point contact.

On-Chip Microwave Quantum Hall Circulator

“…[28] for details), the velocity of the EMP modes is typically v EMP ∼ 10 5 ms −1 [29,30], some 1000 times slower than the speed of light in the semiconductor dielectric. In order to exploit these EMPs to realize nonreciprocal microwave devices, we first detect their presence in a contactless etched disk of quantum Hall fluid by coupling to a proximal metallic coplanar transmission line (CTL) [31], as shown in Figs. 1(a) and 1(b).…”

“…In order to exploit these EMPs to realize non-reciprocal microwave devices, we first detect their presence in a contactless etched disk of quantum Hall fluid by coupling to a proximal metallic coplanar transmission line (CTL) [24], as shown in Fig. 1A and 1B.…”

Fractional charge and fractional statistics in the quantum Hall effects

“…Much attention has focused on Coulomb blockade physics [261][262][263], which is closely related to the interferometry ideas addressed above. Other proposals include the use of the Kondo effect in a quantum dot, coupled to a quantum Hall edge [264], and a proposed experiment to use a quantum dot transport to distinguish FQH states from their particle-hole conjugates [265]. Neutral modes could be detected with momentum resolved tunneling into the edges [266][267][268], but this technique requires very weak disorder.…”

Long-range entanglement for spin qubits via quantum Hall edge modes

“…This effect has been studied in Refs. 37,64 . In the frequency range we are considering, it is predicted that the piezoelectric coupling dominates, in which case the intrinsic Q is independent of the size of the QH disc.…”

“…Since our proposed system of two-qubit entanglement via QH edge modes makes use of an electrostatic interaction rather than the magnetic interaction in Reference 35, our system requires that the electron tunnelling into and out of the edge modes be prohibited. Our proposed two-qubit entangling gate is based on a coupling of the electric dipole of the qubit, which is state-dependent, with the edge modes of the QH droplet described as a quantum harmonic oscillator 36,37 . We obtain a qubitstate-dependent force on the oscillator, resulting in a general form of coupling that has been used for entangling gates in a variety of other physical systems, including trapped ions [38][39][40] and longitudinally-coupled circuit QED qubits [41][42][43] .…”