Neural-Network Decoders for Measurement Induced Phase Transitions
Abstract: Open quantum systems have been shown to host a plethora of exotic dynamical phases.
Hybrid Quantum Photonic Circuits and Quantum Frequency Conversion
Abstract: The ability to generate, detect and manipulate photons with high fidelity is of critical importance for both fundamental quantum optics studies and practical device applications. Quantum frequency conversion, in particular, is in great demand for bridging the carrier frequency gaps in quantum networks and hybrid quantum systems. The efficiency of photon control including quantum frequency conversion is dictated by photon-photon interaction in a nonlinear optical media.
Frequency Metrology with Ultracold Molecules
Abstract: Ultracold atom technologies have transformed our ability to perform high-precision spectroscopy and apply it to time and frequency metrology. Many of the highest-performing atomic clocks are based on laser-cooled atoms trapped in optical lattices. These clocks can be applied to fundamental questions, for example to improve our understanding of gravity and general relativity. In this talk, I will discuss using lattice-trapped ultracold diatomic molecules, rather than atoms, as a reference for clocks. Molecules have more internal quantum states and therefore are relatively chall
Cavity QED from Manybody Physics to Transduction
Abstract: In this talk, I will describe recent developments in the Simon/Schuster collaboration, where we are harnessing cavity quantum electrodynamics for both manybody physics and quantum information. I will begin with an overview of our photonic quantum materials efforts, highlighting the analogy between photons in a lattice of cavities (or family of cavity modes) and electrons in solids.
Quantum Optics with Free Electrons
Abstract: Until recently, work in quantum optics focused on light interacting with bound-electron systems such as atoms, quantum dots, and nonlinear optical crystals. In contrast, free-electron systems enable fundamentally different physical phenomena, as their energy distribution is continuous and not discrete, allowing for tunable transitions and selection rules.
Using circularly polarized light or stirring to control topological memory in a Chern insulator or induced direct current of neutral atoms in an optical lattice
Abstract: Under suitable experimental conditions, some twisted graphene multilayers and transition-metal dichalcogenides become Chern insulators, exhibiting the anomalous quantum Hall effect and orbital magnetization due to spontaneous valley polarization. We study (theoretically) the interaction of a Chern insulator with circularly polarized light, originating from the optical Stark energy shift. The interaction energy contains an antisymmetric term that couples the helicity of incident light and the Berry curvature of the electronic system.
A Tale of Two Disciplines: Non-Abelian Eigenstate Thermalization Hypothesis
Abstract: Why do chaotic quantum many-body systems thermalize internally? The eigenstate thermalization hypothesis (ETH) explains why if the Hamiltonian lacks degeneracies. If the Hamiltonian conserves one quantity ("charge"), the ETH implies thermalization within an eigenspace of the charge—in a microcanonical subspace. However, quantum systems can have charges that fail to commute with each other and so share no eigenbasis; microcanonical subspaces may not exist. Worse, the Hamiltonian will have degeneracies, so the ETH need not imply thermalization.
Building Quantum Networks from Space
Abstract: The SpooQy-1 project designed, built and operated a source of polarisation entangled photon-pairs onboard a CubeSat for over 600 days. From the lessons learned in the SpooQy-1 mission, the Singapore-based team is working towards performing entanglement distribution from a small satellite to ground receivers. In this talk, I will share observations about the performance of the satellite, the entangled photon source, and the single photon detectors in orbit. These data has been used to validate some very useful models for predicting the effect of radiation on components.
Enhancement of superconductivity with external phonon squeezing
Abstract: Squeezing of phonons due to the nonlinear coupling to electrons is a way to enhance superconductivity. In this talk I will present a model of quadratic electron-phonon interaction in the presence of phonon pumping and an additional external squeezing. I will show that the interference between the two driving sources can lead to a stronger electron-electron attraction. This allows for the enhancement of superconductivity, which is shown to be maximal on the boundary with the dynamic lattice instabilities caused by driving.
Precision-enhanced displacement measurements using correlated photon pairs
Abstract: Split detection is a standard experimental scheme for measuring positional displacements. In a typical setup, a laser beam is reflected from the object being probed and then sent to a photodetector that is split into left (L) and right (R) halves: the normalized difference signal (R-L)/(R+L) is then proportional to the object’s horizontal displacement. The maximum precision achievable using this method is limited by the inverse of the beam width.