Many-Body Localization in the Massless Schwinger Model

Local gauge symmetry is intriguing for the study of quantum thermalization breaking. For example, in the high-spin lattice Schwinger model (LSM), the local U(1) gauge symmetry underlies the disorder-free many-body localization (MBL) dynamics of matter fields. This mechanism, however, would not work in a spin- $\frac{1}{2}$ LSM due to the absence of electric energy in the Hamiltonian. In this paper, we show that the spin- $\frac{1}{2}$ LSM can also exhibit disorder-free MBL dynamics, as well as entropy prethermalization, by introducing a four-fermion interaction into the system. The interplay between the fermion interaction and U(1) gauge symmetry endows the gauge fields with an effectively disordered potential which is responsible for the thermalization breaking. It induces anomalous (i.e., nonthermal) behaviors in the long-time evolution of such quantities as local observables, entanglement entropy, and correlation functions. Our work offers a different platform to explore emergent nonthermal dynamics in state-of-the-art quantum simulators with gauge symmetries.Local gauge symmetry is intriguing for the study of quantum thermalization breaking. For example, in the high-spin lattice Schwinger model (LSM), the local U(1) gauge symmetry underlies the disorder-free many-body localization (MBL) dynamics of matter fields. This mechanism, however, would not work in a spin-$\frac{1}{2}$ LSM due to the absence of electric energy in the Hamiltonian. In this paper, we show that the spin-$\frac{1}{2}$ LSM can also exhibit disorder-free MBL dynamics, as well as entropy prethermalization, by introducing a four-fermion interaction into the system. The interplay between the fermion interaction and U(1) gauge symmetry endows the gauge fields with an effectively disordered potential which is responsible for the thermalization breaking. It induces anomalous (i.e., nonthermal) behaviors in the long-time evolution of such quantities as local observables, entanglement entropy, and correlation functions. Our work offers a different platform to explore emergent nonthermal dynamics in state-of-the-art quantum simulators with gauge symmetries.

arXiv:2301.03006Physical review. B./Physical review. BMar 8, 20237 citations

Dynamical Many-Body Localization in an Integrable Model

Aydın Cem Keser

Springer thesesJan 1, 20181 citation

Antiferromagnetic S=12 Heisenberg chain and the two-flavor massless Schwinger model

Yutaka Hosotani

An antiferromagnetic $S=\frac{1}{2}$ Heisenberg chain is mapped to the two-flavor massless Schwinger model at $\ensuremath{\theta}=\ensuremath{\pi}.$ The electromagnetic coupling constant and velocity of light in the Schwinger model are determined in terms of the Heisenberg coupling and lattice spacing in the spin chain system.An antiferromagnetic $S=\frac{1}{2}$ Heisenberg chain is mapped to the two-flavor massless Schwinger model at $\ensuremath{\theta}=\ensuremath{\pi}.$ The electromagnetic coupling constant and velocity of light in the Schwinger model are determined in terms of the Heisenberg coupling and lattice spacing in the spin chain system.

arXiv:hep-th/9809066Physical review. B, Condensed matterSep 1, 19994 citations

Many-body localization and quantum thermalization

Ehud Altman

Nature PhysicsSep 25, 201892 citations

Many-body localization in the quantum random energy model

Chris R. Laumann, Arijeet Pal

Bulletin of the American Physical SocietyMar 3, 20140 citations

T-mu phase diagram using classical-quantum hybrid algorithm

Akio Tomiya

We study the Schwinger model at finite temperature and density using a variational algorithm for near-term quantum devices. We adapt $\beta$ -VQE, a classical-quantum hybrid algorithm with a neural network, to evaluate thermal and quantum expectation values and study the phase diagram for the massless Schwinger model along with the temperature and density. By comparing the exact variational free energy, we find that the variational algorithm works for the Schwinger model for $T>0$ and $\mu$ >0. As a result, we obtain a qualitative picture of the phase diagram for the massless Schwinger model.We study the Schwinger model at finite temperature and density using a variational algorithm for near-term quantum devices. We adapt $\beta$-VQE, a classical-quantum hybrid algorithm with a neural network, to evaluate thermal and quantum expectation values and study the phase diagram for the massless Schwinger model along with the temperature and density. By comparing the exact variational free energy, we find that the variational algorithm works for the Schwinger model for $T>0$ and $\mu$>0. As a result, we obtain a qualitative picture of the phase diagram for the massless Schwinger model.

International Symposium on Lattice Field Theory (LATTICE)Jan 6, 20231 citation

\frac{1}{2}

LSM due to the absence of electric energy in the Hamiltonian. In this paper, we show that the spin-

\frac{1}{2}

LSM can also exhibit disorder-free MBL dynamics, as well as entropy prethermalization, by introducing a four-fermion interaction into the system. The interplay between the fermion interaction and U(1) gauge symmetry endows the gauge fields with an effectively disordered potential which is responsible for the thermalization breaking. It induces anomalous (i.e., nonthermal) behaviors in the long-time evolution of such quantities as local observables, entanglement entropy, and correlation functions. Our work offers a different platform to explore emergent nonthermal dynamics in state-of-the-art quantum simulators with gauge symmetries.

An antiferromagnetic

S=\frac{1}{2}

Heisenberg chain is mapped to the two-flavor massless Schwinger model at $\ensuremath{\theta}=\ensuremath{\pi}.$ The electromagnetic coupling constant and velocity of light in the Schwinger model are determined in terms of the Heisenberg coupling and lattice spacing in the spin chain system.

We study the Schwinger model at finite temperature and density using a variational algorithm for near-term quantum devices. We adapt

\beta

-VQE, a classical-quantum hybrid algorithm with a neural network, to evaluate thermal and quantum expectation values and study the phase diagram for the massless Schwinger model along with the temperature and density. By comparing the exact variational free energy, we find that the variational algorithm works for the Schwinger model for

T>0

and

\mu

>0. As a result, we obtain a qualitative picture of the phase diagram for the massless Schwinger model.