RQS Seminar

Gauge theory is a powerful theoretical framework for understanding the fundamental forces in the standard model. Simulating the real time dynamics of gauge theory, especially in the strong coupling regime, is a challenging classical problem. Quantum computers offer a solution to this problem by taking advantage of the intrinsic quantum nature of the systems. The Schwinger model, that is the 1+1 dimensional U(1) gauge theory coupled to fermions, has served as a testbed for different methods of quantum simulation.

How to write successful grant proposals, pushing your writing skills to the next level. Our speaker will provide an overview of grant writing and discuss successful strategies. Come prepared with your questions.

You can send your questions in advance to rqs-seed@umiacs.umd.edu.

Lunch will be provided.

Quantum devices hold promise to outperform classical computers in performing some physical simulations in the nearest future, making them a valuable tool for physics research. In this talk, Oles will focus on quantum simulation of the topological states of matter hosting Majorana modes – the exotic “half-electron” states. He will show the results obtained from noisy quantum hardware provide us with accurate prediction of Majorana mode wavefunctions. This experiment also allows us to verify the topological nature of observed modes.

This presentation introduces a family of identities that express general linear non-unitary evolution operators as a linear combination of unitary evolution operators, each solving a Hamiltonian simulation problem. This formulation can exponentially enhance the accuracy of the recently introduced linear combination of Hamiltonian simulation (LCHS) method [An, Liu, and Lin, Physical Review Letters, 2023].

Noise is widely regarded as a major obstacle to quantum computing. Fortunately, this problem can be solved efficiently due to the existence of the threshold theorem. It states that under sufficiently weak noise and universal assumptions, there always exists an active quantum error correction protocol with only logarithmic hardware overhead. One may ask: can a similar result be obtained for autonomous (passive) error correction, where noise is suppressed by natural or engineered dissipation?

Noncommuting conserved quantities have recently launched a subfield of quantum thermodynamics. In conventional thermodynamics, a system of interest and an environment exchange quantities—energy, particles, electric charge, etc.—that are globally conserved and are represented by Hermitian operators. These operators were implicitly assumed to commute with each other, until a few years ago. Freeing the operators to fail to commute has enabled many theoretical discoveries—about reference frames, entropy production, resource-theory models, etc.

Suppressing errors is the central challenge for quantum computers to become practically relevant. The paradigmatic approach to this is quantum error correction, which uses quantum codes—redundantly encoded ‘logical qubits’—in combination with repeated rounds of error detection and correction. In this work, we report the realization of a quantum processor whose fundamental processing units are such logical qubits. The processor is based on reconfigurable arrays of neutral atoms in optical tweezers.

Existing schemes for demonstrating quantum computational advantage are subject to various practical restrictions, including the hardness of verification and challenges in experimental implementation. Meanwhile, analog quantum simulators have been realized in many experiments to study novel physics.

One of the most striking many-body phenomena in nature is the sudden change of macroscopic properties as the temperature or energy reaches a critical value. Such equilibrium transitions have been predicted and observed in two and three spatial dimensions, but have long been thought not to exist in one-dimensional (1D) systems.

A central goal in quantum error correction is to reduce the overhead of fault-tolerant quantum computing by increasing noise thresholds and reducing the number of physical qubits required to sustain a logical qubit. In this talk, I will introduce a potential path towards this goal based on a family of dynamically generated quantum error correcting codes that we call “hyperbolic Floquet codes.” These codes are defined by a specific sequence of non-commuting two-body measurements arranged periodically in time that stabilize a topological code on a hyperbolic manifold with negative curvature.