JQI-QuICS-CMTC Seminar

We propose an experimental scheme to construct an optical lattice where the atoms are confined to the surface of a torus. This construction can be realized with spatially shaped laser beams which could be realized with recently developed high resolution imaging techniques. We numerically study the feasibility of this proposal by calculating the tunneling strengths for atoms in the torus lattice.

Building future hybrid quantum networks will require
interfacing different types of quantum systems. Photonic interconnects
between such systems have rarely been investigated due to difficulties
such as spectral mismatch. In this talk, I will discuss our progress
on interfacing photons emitted from a trapped ion with neutral
rubidium atoms. Using quantum frequency conversion, we convert 493 nm

Abstract: In this talk, I will present results from our recent work where we propose a practical way to probe quantum phase transitions in integrable and nearly integrable quantum many-body systems via quench dynamics. Our results are important for quantum simulation experiments because, in these experiments, it is usually difficult to prepare ground states but easy to probe quench dynamics.

In this talk I will describe a recent experiment involving an uncommon realization of individual one-dimensional Bose gases (1DBGs) using a single high aspect-ratio dipole trap. While this realization aims to enable the study of multi-component, strongly interacting bosons in 1D, we start by fully characterizing the thermodynamic state of a much simpler, single-component, interacting 1DBG via its equation of state.

A chain of Josephson junctions implements one of the simplest many-body models undergoing a superconductor-insulator quantum phase transition between states with zero and infinite resistance. Apart from zero resistance, the superconducting state is necessarily accompanied by a sound-like phase mode due to collective oscillations of the phase of the complex-valued order parameter. Exciting the phase mode results in transverse photons propagating along the chain.

We study, theoretically and experimentally, electromagnetically induced transparency (EIT) in two different solid-state systems. We observe EIT lineshapes typical of atomic gases, including a crossover into the regime of Autler-Townes splitting, but with the substitution of the inhomogeneous widths for the homogeneous widths. We obtain quantitative agreement between experiment and theory for the width of the transparency feature over a range of optical powers and inhomogeneous linewidths.

As we seek to scale up small quantum devices into general-purpose quantum computers, we will need to develop also the tools for designing large-scale architectures. In this talk I will discuss some of the challenges involved in trying to evaluate different potential architectures and introduce a family of graphs called hierarchies which seem like excellent candidates.

We illustrate the existence of single-excitation bound states for propagating photons interacting with N two-level atoms. These bound states can be calculated from an effective spin model, and their existence relies on dissipation in the system. The appearance of these bound states is in a one-to-one correspondence with zeros in the single-photon transmission  and with divergent  bunching in the second-order photon-photon correlation function.

Multi-scale entanglement renormalization ansatz (MERA) is a quantum circuit that renormalizes entanglement in real space at different length scales. It is widely believed that chiral topologically ordered states cannot have a scale-invariant MERA circuit. In this talk, we show that the continuous MERA (cMERA), a modified version of MERA adapted for field theories, possesses a fixed point wavefunction with nonzero Chern number.

Quantum simulations provide a testbed to study a broad range of problems in physics, chemistry, and biology. We propose an ion trap scheme to quantum simulate a para-particle oscillator of even order. Our quantum simulation starts from the cross-cavity quantum Rabi model. Resonant fields and homogeneous coupling constants allow us to recover an effective Hamiltonian where the first (second) boson field mode couples to the two-level system under (anti-)Jaynes-Cummings dynamics, that can be map into a driven para-Bose oscillator of even order.