Molecular beam epitaxy growth of quantum devices

The inherent fragility and surface/interface-sensitivity of quantum devices demand fabrication techniques under very clean environment.Here,I briefly introduces several techniques based on molecular beam epitaxy growth on pre-patterned substrates which enable us to directly prepare in-plane nanostructures and heterostructures in ultrahigh vacuum.The molecular beam epitaxy-based fabrication techniques are especially useful in constructing the high-quality devices and circuits for solid-state quantum computing in a scalable way.

Classical-Noise-Free Sensing Based on Quantum Correlation Measurement

Quantum sensing,using quantum properties of sensors,can enhance resolution,precision,and sensitivity of imaging,spectroscopy,and detection.An intriguing question is:Can the quantum nature(quantumness)of sensors and targets be exploited to enable schemes that are not possible for classical probes or classical targets?Here we show that measurement of the quantum correlations of a quantum target indeed allows for sensing schemes that have no classical counterparts.As a concrete example,in the case that the second-order classical correlation of a quantum target could be totally concealed by non-stationary classical noise,the higher-order quantum correlations can single out a quantum target from the classical noise background,regardless of the spectrum,statistics,or intensity of the noise.Hence a classical-noise-free sensing scheme is proposed.This finding suggests that the quantumness of sensors and targets is still to be explored to realize the full potential of quantum sensing.New opportunities include sensitivity beyond classical approaches,non-classical correlations as a new approach to quantum many-body physics,loophole-free tests of the quantum foundation,et cetera.

Perfect photon absorption based on the optical parametric process

The perfect photon absorption is studied in a cavity quantum electrodynamics(CQED) system, in which an optical parameter amplifier(OPA) is coupled to the cavity mode. This makes it possible to control the optical phase to realize the perfect photon absorption. It is found that in the presence of one and two injected fields, the perfect photon absorption is present in these two cases and can be controlled by adjusting the parametric phase. Moreover, different from the previous predictions of perfect photon absorption in atomic CQED systems, the perfect photon absorption can be changed significantly by the relative phase. Our work provides a new platform to use the parametric processes to make an available way to control the behaviors of photons and to take advantage of the optical phase to achieve the perfect photon absorption.

Reduced Crossed Products of Pro-Banach Algebras

This paper gives the concept of the reduced pro-Banach algebra crossed product associated with inversely pro-Banach algebra dynamical system,and shows that the reduced crossed product is an inverse limit of an inverse system of Banach algebra crossed products.Also,the authors show that if the locally compact group is amenable,then the crossed product and the reduced crossed product are isometrically isomorphic.

Three ultracold fermions in a two-dimensional anisotropic harmonic confinement

We calculate the energy spectrum of three identical fermionic ultracold atoms in two different internal states confined in a two-dimensional anisotropic harmonic trap.Using the solutions of the corresponding two-body problems obtained in our previous work(Chen et al 2020 Phys.Rev.A 101,053624),we derive the explicit transcendental equation for the eigen-energies,from which the energy spectrum is derived.Our results can be used for the calculation of the 3rd Virial coefficients or the studies of few-body dynamics.