Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1706.00184

Topology-Induced Symmetry Breaking for Vortex with Artificial Monopole

Zixian Zhou, Zhi-Guo Lü, Hang Zheng

Published Jun 1, 2017• 0 citations
arXivHTMLPDF

Abstract

We construct an artificial U(1) gauge field in the cold atom system to form a monopole along with vortices. It is supposed that the cold atoms are confined on a spherical surface, and two sets of identical laser beams in the opposite propagating directions shine on two sides of the sphere. Arbitrary Chern number CN, proportional to the quantized magnetic flux, can be obtained by selecting proper laser modes. This construction meets the condition of Chern's theorem, so that the vortices of the atom wave function will emerge on the sphere, whose winding number equals CN. It is found that a geometric symmetry is broken spontaneously for odd CN, which corresponds to a topology-induced quantum phase transition. In particular for CN=1, the ground state of the cold atoms are double-degenerate and can be applied to make a stable qubit. Since the ground-state degeneracy is protected by topology-induced symmetry breaking against dissipation, the proposed topological structure has vast potential in quantum storage.

DOI
10.48550/arxiv.1706.00184

Related papers

Flux lattices reformulated

Gediminas Juzeliūnas, I B Spielman

We theoretically explore the optical flux lattices produced for ultra-cold atoms subject to laser fields where both the atom-light coupling and the effective detuning are spatially periodic. We analyze the geometric vector potential and the magnetic flux it generates, as well as the accompanying geometric scalar potential. We show how to understand the gauge-dependent Aharonov-Bohm singularities in the vector potential, and calculate the continuous magnetic flux through the elementary cell in terms of these singularities. The analysis is illustrated with a square optical flux lattice. We conclude with an explicit laser configuration yielding such a lattice using a set of five properly chosen beams with two counterpropagating pairs (one along the x axes and the other y axes), together with a single beam along the z axis. We show that this lattice is not phase-stable, and identify the one phase-difference that affects the magnetic flux. Thus armed with realistic laser setup, we directly compute the Chern number of the lowest Bloch band to identify the region where the non- zero magnetic flux produces a topologically non-trivial band structure.

arXiv:1207.2657•New Journal of Physics•Dec 12, 2012•24 citations

The synthetic gauge field and exotic vortex phase with spin-orbital-angular-momentum coupling

Y. Q. Liu, Yun Chen, Yuangang Deng

Abstract Ultracold atoms endowed with tunable spin-orbital-angular-momentum coupling (SOAMC) represent a promising avenue for delving into exotic quantum phenomena. Building on recent experimental advancements, we propose the generation of synthetic gauge fields, and by including exotic vortex phases within spinor Bose–Einstein condensates, employing a combination of a running wave and Laguerre–Gaussian laser fields. We investigate the ground-state characteristics of the SOAMC condensate, revealing the emergence of exotic vortex states with controllable orbital angular momenta. It is shown that the interplay of the SOAMC and conventional spin-linear-momentum coupling induced by the running wave beam leads to the formation of a vortex state exhibiting a phase stripe hosting single multiply quantized singularity. The phase of the ground state will undergo the phase transition corresponding to the breaking of rotational symmetry while preserving the mirror symmetry. Importantly, the observed density distribution of the ground-state wavefunction, exhibiting broken rotational symmetry, can be well characterized by the synthetic magnetic field generated through light interaction with the dressed spin state. Our findings pave the way for further exploration into the rotational properties of stable exotic vortices with higher orbital angular momenta against splitting in the presence of synthetic gauge fields in ultracold quantum gases.

arXiv:2406.20001•Communications in Theoretical Physics•May 20, 2024•1 citation

Topological Domain-Wall Pump with Z 2 Spontaneous Symmetry Breaking

Yoshihito Kuno, Yasuhiro Hatsugai

A domain-wall pump by an extended cluster model of S=1/2 spins is proposed with local U(1) gauge invariance. In contrast to the conventional pump, the current and the gauge field are defined on sites instead of links. Its snapshot ground state is gapped and doubly degenerated due to Z_{2} invariance, which is broken by an infinitesimal boundary magnetic field. The ground state associated with the spontaneous symmetry breaking is, at the same time, symmetry-protected with additional spatial inversion that is characterized by the Z_{2} Berry phase defined by the twist on the boundary site. We investigate the topological domain-wall pump with and without boundaries. The topological pump associated with the inversion symmetry-breaking path induces a nontrivial Chern number of bulk and a singular behavior of edge states of the domain wall. Generalization to the multispin interaction is also explicitly given. These extended quantum degrees of freedom are prominent qubits that are topologically protected.

Physical Review Letters•Jun 5, 2025•1 citation

Observation of a symmetry-protected topological phase in external magnetic fields

Zhihuang Luo, Wen-Zhao Zhang, Xinfang Nie +1 more

Topological phases have greatly improved our understanding of modern conception of phases of matter that go beyond the paradigm of symmetry breaking and are not described by local order parameters. Instead, characterization of topological phases requires the robust topological invariants, whereas measuring these global quantities presents an outstanding challenge for experiments, especially in interacting systems. Here we report the real-space observation of a symmetry-protected topological phase with interacting nuclear spins, and probe the interaction-induced transition between two topologically distinct phases, both of which are classified by many-body Chern numbers obtained from the dynamical response to the external magnetic fields. The resulting value of Chern number ($\bar{\mathcal{C}h} = 1.958 \pm 0.070$) demonstrates the robust ground state degeneracy, and also determines the number of nontrivial edge states. Our findings enable direct characterization of topological features of quantum many-body states through gradually decreasing the strength of the introduced external fields.

arXiv:2208.05357•Aug 10, 2022•0 citations

Designing Yang–Mills Topological Vacua with Cold Atoms

Shi-Liang Zhu

Abstract Topological vacua, a family of degenerate ground states of the Yang–Mills fields with zero field strength but nontrivial topological structures, play a fundamental role in particle physics and quantum field theory. However, they have not yet been experimentally observed. Here, we propose an experimental scheme to realize a real-space SU (2) artificial Yang–Mills topological vacua using a cloud of two-Λ-level cold atoms. We derive analytical expressions for the gauge transformations and gauge potentials of these topological vacua. Specifically, we propose a degenerate subspace that supports Yang–Mills gauge fields and identify the laser configurations required to realize the topological vacua. Furthermore, we generalize the vacua to a family with a topological number given by the product of two integers. We also propose an Aharonov–Bohm interference experiment to detect the resulting geometric phases, which persist even with vanishing gauge field strengths throughout space, distinct from the electromagnetic case.

Chinese Physics Letters•Mar 16, 2026•1 citation

Spin-orbit coupling and topological states in an F=32 cold Fermi gas

Igor Kuzmenko, Tetyana Kuzmenko, Y. Avishai +1 more

In this work we study the possible occurrence of topological insulators for 2D fermions of high spin. They can be realized in cold fermion systems with ground-state atomic spin $F>\frac{1}{2}$, if the optical potential is properly designed, and spin-orbit coupling is relevant. The latter is shown to be induced by letting the fermions interact with a specially tuned arrangement of polarized laser beams. When the system is subject to a perpendicular magnetic field, time reversal symmetry is broken but the ensuing Hamiltonian is still endowed with a mirror symmetry. Topological insulators for fermions of higher spins are fundamentally distinct from those pertaining to spin $\frac{1}{2}$. The underlying physics reveals a plethora of positive and negative mirror Chern numbers, respectively, corresponding to chiral and antichiral edge states. Here, for simplicity, we concentrate on the case $F=\frac{3}{2}$ (which is suitable for $^{6}\mathrm{Li}$ or $^{2}\mathrm{H}$ atoms) but extension to higher spins (such as $^{40}\mathrm{K}$ whose ground-state spin is $F=\frac{9}{2}$) is straightforward.

arXiv:1801.05646•Physical review. B./Physical review. B•Oct 26, 2018•7 citations
We construct an artificial U(1) gauge field in the cold atom system to form a monopole along with vortices. It is supposed that the cold atoms are confined on a spherical surface, and two sets of identical laser beams in the opposite propagating directions shine on two sides of the sphere. Arbitrary Chern number CN, proportional to the quantized magnetic flux, can be obtained by selecting proper laser modes. This construction meets the condition of Chern's theorem, so that the vortices of the atom wave function will emerge on the sphere, whose winding number equals CN. It is found that a geometric symmetry is broken spontaneously for odd CN, which corresponds to a topology-induced quantum phase transition. In particular for CN=1, the ground state of the cold atoms are double-degenerate and can be applied to make a stable qubit. Since the ground-state degeneracy is protected by topology-induced symmetry breaking against dissipation, the proposed topological structure has vast potential in quantum storage.
We theoretically explore the optical flux lattices produced for ultra-cold atoms subject to laser fields where both the atom-light coupling and the effective detuning are spatially periodic. We analyze the geometric vector potential and the magnetic flux it generates, as well as the accompanying geometric scalar potential. We show how to understand the gauge-dependent Aharonov-Bohm singularities in the vector potential, and calculate the continuous magnetic flux through the elementary cell in terms of these singularities. The analysis is illustrated with a square optical flux lattice. We conclude with an explicit laser configuration yielding such a lattice using a set of five properly chosen beams with two counterpropagating pairs (one along the x axes and the other y axes), together with a single beam along the z axis. We show that this lattice is not phase-stable, and identify the one phase-difference that affects the magnetic flux. Thus armed with realistic laser setup, we directly compute the Chern number of the lowest Bloch band to identify the region where the non- zero magnetic flux produces a topologically non-trivial band structure.
Abstract Ultracold atoms endowed with tunable spin-orbital-angular-momentum coupling (SOAMC) represent a promising avenue for delving into exotic quantum phenomena. Building on recent experimental advancements, we propose the generation of synthetic gauge fields, and by including exotic vortex phases within spinor Bose–Einstein condensates, employing a combination of a running wave and Laguerre–Gaussian laser fields. We investigate the ground-state characteristics of the SOAMC condensate, revealing the emergence of exotic vortex states with controllable orbital angular momenta. It is shown that the interplay of the SOAMC and conventional spin-linear-momentum coupling induced by the running wave beam leads to the formation of a vortex state exhibiting a phase stripe hosting single multiply quantized singularity. The phase of the ground state will undergo the phase transition corresponding to the breaking of rotational symmetry while preserving the mirror symmetry. Importantly, the observed density distribution of the ground-state wavefunction, exhibiting broken rotational symmetry, can be well characterized by the synthetic magnetic field generated through light interaction with the dressed spin state. Our findings pave the way for further exploration into the rotational properties of stable exotic vortices with higher orbital angular momenta against splitting in the presence of synthetic gauge fields in ultracold quantum gases.
A domain-wall pump by an extended cluster model of S=1/2 spins is proposed with local U(1) gauge invariance. In contrast to the conventional pump, the current and the gauge field are defined on sites instead of links. Its snapshot ground state is gapped and doubly degenerated due to Z_{2} invariance, which is broken by an infinitesimal boundary magnetic field. The ground state associated with the spontaneous symmetry breaking is, at the same time, symmetry-protected with additional spatial inversion that is characterized by the Z_{2} Berry phase defined by the twist on the boundary site. We investigate the topological domain-wall pump with and without boundaries. The topological pump associated with the inversion symmetry-breaking path induces a nontrivial Chern number of bulk and a singular behavior of edge states of the domain wall. Generalization to the multispin interaction is also explicitly given. These extended quantum degrees of freedom are prominent qubits that are topologically protected.
Topological phases have greatly improved our understanding of modern conception of phases of matter that go beyond the paradigm of symmetry breaking and are not described by local order parameters. Instead, characterization of topological phases requires the robust topological invariants, whereas measuring these global quantities presents an outstanding challenge for experiments, especially in interacting systems. Here we report the real-space observation of a symmetry-protected topological phase with interacting nuclear spins, and probe the interaction-induced transition between two topologically distinct phases, both of which are classified by many-body Chern numbers obtained from the dynamical response to the external magnetic fields. The resulting value of Chern number (Chˉ=1.958±0.070\bar{\mathcal{C}h} = 1.958 \pm 0.070Chˉ=1.958±0.070) demonstrates the robust ground state degeneracy, and also determines the number of nontrivial edge states. Our findings enable direct characterization of topological features of quantum many-body states through gradually decreasing the strength of the introduced external fields.
Abstract Topological vacua, a family of degenerate ground states of the Yang–Mills fields with zero field strength but nontrivial topological structures, play a fundamental role in particle physics and quantum field theory. However, they have not yet been experimentally observed. Here, we propose an experimental scheme to realize a real-space SU (2) artificial Yang–Mills topological vacua using a cloud of two-Λ-level cold atoms. We derive analytical expressions for the gauge transformations and gauge potentials of these topological vacua. Specifically, we propose a degenerate subspace that supports Yang–Mills gauge fields and identify the laser configurations required to realize the topological vacua. Furthermore, we generalize the vacua to a family with a topological number given by the product of two integers. We also propose an Aharonov–Bohm interference experiment to detect the resulting geometric phases, which persist even with vanishing gauge field strengths throughout space, distinct from the electromagnetic case.
In this work we study the possible occurrence of topological insulators for 2D fermions of high spin. They can be realized in cold fermion systems with ground-state atomic spin F>12F>\frac{1}{2}F>21​, if the optical potential is properly designed, and spin-orbit coupling is relevant. The latter is shown to be induced by letting the fermions interact with a specially tuned arrangement of polarized laser beams. When the system is subject to a perpendicular magnetic field, time reversal symmetry is broken but the ensuing Hamiltonian is still endowed with a mirror symmetry. Topological insulators for fermions of higher spins are fundamentally distinct from those pertaining to spin 12\frac{1}{2}21​. The underlying physics reveals a plethora of positive and negative mirror Chern numbers, respectively, corresponding to chiral and antichiral edge states. Here, for simplicity, we concentrate on the case F=32F=\frac{3}{2}F=23​ (which is suitable for 6Li^{6}\mathrm{Li}6Li or 2H^{2}\mathrm{H}2H atoms) but extension to higher spins (such as 40K^{40}\mathrm{K}40K whose ground-state spin is F=92F=\frac{9}{2}F=29​) is straightforward.