High Energy Physics from Low Energy Physics

TL;DR

This thesis explores the relationship between low and high energy physics through UV/IR symmetry and quantum computer simulations of lattice gauge theories, advancing understanding and computational methods in quantum field theory.

Contribution

It introduces physics-aware quantum simulation methods for lattice gauge theories and demonstrates the first real-time simulation of lattice QCD on a quantum computer.

Findings

Low energy nuclear physics nearly exhibits UV/IR symmetry.

First quantum computer simulation of 1D lattice QCD with real-time beta-decay.

Successful simulation of lattice gauge theories on 100+ qubits.

Abstract

The separation between physics at low and high energies is essential for physics to have any utility; the details of quantum gravity are not necessary to calculate the trajectory of a cannon ball. However, physics at low and high energies are not completely independent, and this thesis explores two ways that they are related. The first is through a UV/IR symmetry that relates scattering processes at low and high energies. This UV/IR symmetry manifests in geometrical properties of the $S$-matrix, and of the RG flow of the coupling constants in the corresponding effective field theory. Low energy nuclear physics nearly realizes this UV/IR symmetry, providing an explanation for the smallness of shape parameters in the effective range expansion of nucleon-nucleon scattering, and inspiring a new way to organize the interactions between neutrons and protons. The second is through the use of quantum computers to simulate lattice gauge theories. Quantum simulations rely on the universality of the rules of quantum mechanics, which can be applied equally well to describe a (low energy) transmon qubit at 15 milli-Kelvin as a (high energy) 1 TeV quark. This thesis presents the first simulations of one dimensional lattice quantum chromodynamics on a quantum computer, culminating in a real-time simulation of beta-decay. Results from the first simulations of a lattice gauge theory on 100+ qubits of a quantum computer are also presented. The methods developed in this thesis for quantum simulation are ``physics-aware", and are guided by the symmetries and hierarchies in length scales of the systems being studied. Without these physics-aware methods, 100+ qubit simulations of lattice gauge theories would not have been possible on the noisy quantum computers that are presently available.