JQI

Abstract: Over the past few decades, concurrent advances in experimental techniques in both quantum information science (QIS) and physical chemistry have enabled unprecedented control over simple molecules, both in terms of their lab-frame motions and their internal quantum states. In this talk, I will discuss the potential for these well-controlled molecules to advance two fundamental areas of physical chemistry: structure and dynamics.

Abstract: The last few years have seen a remarkable development in our ability to control many neutral atoms individually, and induce controlled interactions between them on demand. This progress ushers in a new era where one can create highly entangled states, overcome certain limits of quantum measurements using entangled states, or study quantum phase transitions. I will present results on atomic arrays containing hundreds of individually trapped atoms, and first steps towards quantum computation with error detection and correction.

Abstract: The Hubbard model of attractively interacting fermions provides a paradigmatic setting for fermion pairing, featuring a crossover between Bose-Einstein condensation (BEC) of tightly bound pairs and Bardeen-Cooper-Schrieffer (BCS) superfluidity of long-range Cooper pairs, and a "pseudo-gap" region where pairs form already above the superfluid critical temperature. We directly observe the non-local nature of fermion pairing in a Hubbard lattice gas, employing spin- and density-resolved imaging of ∼1000 fermionic 40K atoms under a bilayer microscope.

Abstract: A basic tenet of quantum theory is that all elementary particles are either bosons or fermions.  Ensembles of bosons or fermions behave differently due to differences in their underlying  quantum statistics. Starting in the early 1980’s it was theoretically conjectured that excitations that are neither bosons nor fermions may exist under special conditions in two-dimensional interacting electron systems. These unusual excitations were dubbed “anyons”.

The unification of quantum mechanics and gravity is a major outstanding goal. One modern approach to understanding this unification goes by the name ``holography’’, in which gravity can be understood as an emergent description of some more fundamental, purely quantum mechanical system. In this talk I will describe some recent results in holography that elucidate how this emergence works. A starring role will be played by one-shot quantum information theory.

Twisted bilayer graphene is a rich condensed matter system, which allows one to tune energy scales and electronic correlations. The low-energy physics of the resulting moiré structure can be mathematically described in terms of a diffeomorphism in a continuum formulation. Twisting is just one example of moiré diffeomorphisms.

Abstract: Light-matter interactions allow adding functionalities to photonic on-chip devices, thus enabling developments in classical and quantum light sources, energy harvesters and sensors. These advances have been facilitated by precise control in growth and fabrication techniques that have opened new pathways to the design and realization of semiconductor devices where light emission, trapping and guidance can be efficiently controlled at the nanoscale.

A fundamental requirement for quantum technologies is the ability to coherently control the interaction between electrons and photons. However, in many scenarios involving the interaction between light and matter, the exchange of linear or angular momentum between electrons and photons is not feasible, a condition known as the dipole-approximation limit.

Noise on quantum devices is much more complex than it is commonly given credit. Far from usual models of decoherence, nearly all quantum devices are plagued both by a continuum of environments and temporal instabilities. These induce noisy quantum and classical correlations at the level of the circuit. The relevant spatiotemporal effects are difficult enough to understand, let alone combat. There is presently a lack of either scalable or complete methods to address the phenomena responsible for scrambling and loss of quantum information.

We propose a new sub-Doppler cooling scheme in trapped ion crystals in Paul traps which utilizes a Sisyphus-like cooling mechanism to simultaneously cool all the motional modes of the crystal. We use a hollow tweezer, tuned near resonance with the transition from the qubit manifold to a short-lived excited manifold, to generate a state-dependent tweezer potential. This tweezer also introduces a position dependent quench rate for the qubit states.