Quantum Simulation of Spin-Boson Models with Structure Bath
Abstract: The spin-boson model, involving spins interacting with a bath of quantum harmonic oscillators, is a widely used representation of open quantum systems that describe many dissipative processes in physical, chemical and biological systems. Trapped ions present an ideal platform for simulating the quantum dynamics of such models, by accessing both the high-quality internal qubit states and the motional modes of the ions for spins and bosons, respectively.
Entanglement witness for combined atom interferometer-mechanical oscillator system
Abstract: D. Carney et al. [https://doi.org/10.1103/PRXQuantum.2.030330] suggest the use of a trapped atom interferometer combined with a mechanical oscillator to test certain theories combining quantum mechanics with gravity. We construct an entanglement witness applicable to the stated interferometer-oscillator setup.
Polynomial-Time Classical Simulation of Noisy IQP Circuits with Constant Depth
Abstract: Sampling from the output distributions of quantum computations comprising only commuting gates, known as instantaneous quantum polynomial (IQP) computations, is believed to be intractable for classical computers, and hence this task has become a leading candidate for testing the capabilities of quantum devices. Here we demonstrate that for an arbitrary IQP circuit undergoing dephasing or depolarizing noise, whose depth is greater than a critical O(1)threshold, the output distribution can be efficiently sampled by a classical computer.
Instability of steady-state mixed symmetry-protected topological order to strong-to-weak spontaneous symmetry breaking
Abstract: We address the question of whether open quantum system dynamics which host mixed symmetry-protected topological (SPT) states as steady states continue to do so after introducing symmetric perturbations. In particular, we discuss the characteristics of the decohered cluster state --- a mixed SPT protected by a combined strong and weak symmetry --- and construct a parent Lindbladian which hosts it as a steady state. The parent Lindbladian can be mapped onto reaction-diffusion dynamics, which is exactly solvable, even in the presence of certain perturbations.
Leaning into Lidar
This story was originally posted by the UMD College of Computer, Mathematical, and Natural Sciences and has been reposted here with permission.
Swarnav Banik’s (Ph.D. ’21, physics) parents were visiting from India when they saw a strange-looking car on a San Francisco street that stopped them in their tracks.
Order-by-disorder in the antiferromagnetic J1-J2-J3 transverse-field Ising model on the ruby lattice
Abstract: Extensively degenerate ground-state spaces due to frustration pose a formidable resource for emergent quantum phenomena. Perturbing extensively degenerate ground-state spaces may result in several distinct scenarios lifting the ground-state degeneracy. First, an infinitesimal perturbation can lead to a symmetry-broken order (order-by-disorder) or second the perturbation can result in a symmetry-unbroken phase (disorder-by-disorder), which can be either trivial or an exotic quantum spin liquid.