The exploration of tunneling dynamics in many-body quantum systems plays a pivotal role in realizing groundbreaking atomtronic devices and achieving precise control over entanglement. Here, we delve into the intricate many-body tunneling dynamics of ultracold atoms confined within a quadruple-well potential, with a particular emphasis on the manipulative role played by interatomic interactions and synthetic gauge fields. The quantum dynamics displayed by the system closely mimic the operations of qudit hybrid gates, which are comprised of two relatively independent sets of qudits. In the Rabi regime, which is characterized by strong coupling, we observe an intriguing phenomenon: the cyclic collapse and revival of discrete tunneling dynamics within two distinct qudits. Notably, this intricate dynamical behavior exhibits remarkable synchronous and anti-synchronous revival features, offering a unique opportunity to engineer many-body synchronization pulse signals. In the resonant tunneling regime, distinguished by strong interatomic interactions, we made a remarkable observation: the hybrid qudits undergo a dimensionality reduction, effectively transforming into a qudit. This dimensionality reduction is accompanied by an intriguing phenomenon: the periodicity of its dynamics is intimately intertwined with the occurrence of the entanglement cycle. Remarkably, synthetic gauge fields emerge as potent regulators of this entanglement cycle. Our results uncover the profound implications of synthetic gauge fields on quantum tunneling processes within many-body systems, which hold promising potential applications for engineering atomtronic devices and controlling quantum entanglement.
The exploration of tunneling dynamics in many-body quantum systems plays a pivotal role in realizing groundbreaking atomtronic devices and achieving precise control over entanglement. Here, we delve into the intricate many-body tunneling dynamics of ultracold atoms confined within a quadruple-well potential, with a particular emphasis on the manipulative role played by interatomic interactions and synthetic gauge fields. The quantum dynamics displayed by the system closely mimic the operations of qudit hybrid gates, which are comprised of two relatively independent sets of qudits. In the Rabi regime, which is characterized by strong coupling, we observe an intriguing phenomenon: the cyclic collapse and revival of discrete tunneling dynamics within two distinct qudits. Notably, this intricate dynamical behavior exhibits remarkable synchronous and anti-synchronous revival features, offering a unique opportunity to engineer many-body synchronization pulse signals. In the resonant tunneling regime, distinguished by strong interatomic interactions, we made a remarkable observation: the hybrid qudits undergo a dimensionality reduction, effectively transforming into a qudit. This dimensionality reduction is accompanied by an intriguing phenomenon: the periodicity of its dynamics is intimately intertwined with the occurrence of the entanglement cycle. Remarkably, synthetic gauge fields emerge as potent regulators of this entanglement cycle. Our results uncover the profound implications of synthetic gauge fields on quantum tunneling processes within many-body systems, which hold promising potential applications for engineering atomtronic devices and controlling quantum entanglement.
Abstract By introducing two opposing driving fields with a reduced electric field strength, we successfully achieve quantum non-reciprocal transport of ultracold atoms confined within a quadruple-well system that incorporates a synthetic gauge field. This achievement not only disrupts the inherent robustness of reciprocal transport in such systems but also underscores the indispensability of coherent drives in facilitating quantum non-reciprocal transport, irrespective of the presence or absence of dissipation. In the absence of dissipation, the interplay between the synthetic gauge field and the driving fields endows the system with the capacity for non-reciprocal transport of ultracold atoms. This finding highlights the significance of unequal reduced field strengths in the genesis of nonreciprocal quantum transport, with the synergistic effects of the synthetic gauge field and coherent drives dictating both the magnitude and direction of the nonreciprocal transport. In the presence of dissipation, although the population and tunneling probability of ultracold atoms are diminished, the non-reciprocity of the system can be amplified by the driving fields and the artificial gauge field. This amplification results in an enhancement of non-reciprocity, allowing for the generation of strong unidirectional non-reciprocal windows through the modulation of the combined effects of dissipation, coherent drives, and the synthetic gauge field. Our findings provide a valuable reference for the development of quantum non-reciprocal routers within ultracold atoms, offering insights into the control and manipulation of quantum transport phenomena.
In this thesis, we study two distinct, yet equally fascinating, aspects of manybody physics. Synthetic quantum matter – engineered many-body systems with high controllability and tunability – serves as a cornerstone for the research. The combination of these features makes them incredibly suited for research at the crossroads of traditional statistical physics, new concepts coming from field theory (particularly gauge theories), and quantum information. In the first part, we delve into the quantum simulation of novel quantum phenomena with analog quantum simulators. In particular, recent advances in the synthetic platforms based on Rydberg atoms, i.e., neutral atoms trapped in optical tweezers, have opened up new avenues to explore exotic topological phases like quantum spin liquids, which hold potential applications in quantum computing. We employ a combination of numerical and analytical tools to address open questions regarding the realization of these phases in experiments. Our results show that the recently observed spin liquids can be directly connected to a Higgs-Ising lattice gauge theory, providing a clear-cut theoretical argument for its origin. Moreover, different setups with chiral interacting Hamiltonians offer new avenues to realize chiral spin liquids - a lattice version of the celebrated quantum Hall effect. In the second part, we explore the role of a quantum information quantity known as nonstabilizerness in quantum many-body systems. By now, the study of quantum information concepts in the realm of many-body theory represents a very active research effort, with a prominent example being entanglement, which has revolutionized our understanding of quantum systems. Similar to entanglement, nonstabilizerness has emerged as a crucial resource for achieving quantum advantage, although in a fundamentally different way. While entanglement is well-studied, the exploration of nonstabilizerness in many-body contexts is still in its very early stages. Its ongoing investigation holds significant promise for deepening our understanding of many-body systems and their complexity. We develop new methods based on tensor networks and Monte Carlo methods to enable the quantification of nonstabilizerness at large scales. We subsequently apply them to uncover the role of nonstabilizerness in various many-body settings, particularly in critical phenomena, gauge theory, and quantum circuits.
Ultracold Bose gases as precise quantum simulators have emerged amongst the leaders in the current race – a second quantum revolution – toward the promise of unfathomable sensitivity, scope, and speed of a new era of technology. The only path leading to these advancements is through many-body descriptions, especially in regimes where interatomic interactions render many approximations incompatible with the physics. The research in this dissertation unlocks a piece of this mystery through investigations of many-body quantum tunneling of ultracold bosons in optical lattices. A key mechanism to characterizing the dynamics, matrix product state simulations equip the many-body toolbox with efficient optimization of large Hilbert spaces together with correlation and entropy measures that help clarify when semiclassical or mean-field approximations fail. In this thesis we obtain the following results. Macroscopic quantum tunneling escape of a Bose-Einstein condensate – comprised of tens of thousands of 87Rb atoms – from a single well, as portrayed through both experiment and theory, highlights non-exponential decay in the number of atoms trapped behind the barrier. Additionally, explicit symmetry breaking of a biperiodic optical lattice ring trap to a uniform one illustrates a critical symmetry-breaking strength at which the system transitions from a state of remembering to a state of forgetting its initial symmetry state; this symmetry memory indicates a new form of quantum dynamics that requires the quantum advantage for scaling up particle number and lattice sites. Extensive characterization of dynamical regimes in a bosonic Josephson junction – underlaid by an optical lattice as described by the Bose-Hubbard model – reveal substantial deviation of many body dynamics from the mean field or semiclassical predictions underlying the usual operating regime of Josephson junctions. Initial state population and phase yield insight into dynamic tunneling regimes of a quasi one-dimensional double well potential, through the Z2 spontaneous symmetry-breaking phase transition from Josephson oscillations to macroscopic self-trapping. We demonstrate that with increasing repulsive interaction strength, the U(1) superfluid-Mott insulator phase transition induces localized dynamics in the number density, such as particle-hole and soliton formation. Moreover, g^(2) correlations unveil a new dynamic regime – the Fock flashlight. The new field of atomtronics – or atomic circuits – has emerged with many studies of weakly-interacting condensates. In contrast, and building on our work on many-body effects in the double wells underlying Josephson junctions, we present a proof-of-principle of a Mott-insulating atomtronic switch that requires strongly-interacting bosons. Through transient analysis, we reveal that hole conductance can be modulated via tuning interaction strength through a critical value, thus propelling the state to the next ``wedding cake'' layer of the Mott insulating structure. This critical interaction strength is a…
Multipartite entanglement lies at the heart of quantum many-body physics and quantum information science, serving as a key resource for quantum computation, quantum simulation, and quantum metrology. While its behavior in Hermitian systems has been extensively studied, its fate in non-Hermitian systems, especially those with synthetic gauge fields, remains largely unexplored. In this work we investigate multipartite entanglement dynamics in a quadruple-well system under the influence of synthetic gauge fields and nonreciprocal coupling. By constructing a many-body Hamiltonian that incorporates synthetic gauge fluxes, interaction-induced nonlinearity, and parity-time (PT) symmetry-breaking terms, we reveal that the interplay between non-Hermiticity and gauge fields provides unprecedented control over entanglement structures and their evolution. Notably, the synthetic gauge field acts as a tunable switch for entanglement configurations, enabling transitions between separable, bipartite, tripartite, and globally entangled configurations. Furthermore, we uncover a striking odd-even effect of particle number on both PT-symmetry phase transitions and entanglement patterns, highlighting the role of particle-number parity in non-Hermitian many-body systems. These findings not only deepen our understanding of many-body quantum correlations in non-Hermitian systems but also open alternative avenues for designing entanglement-resolved quantum sensors and preparing topologically nontrivial many-body states in synthetic quantum platforms.
We investigate the quantum chaos of ultracold atoms in a quadruple-well potential, emphasizing the influence of synthetic gauge fields and many-body atomic interactions on the transitions from regular behavior to quantum chaos. We compare the metrics that the eigenvalue statistics of nearest-neighbor spacings distribution and gap ratio analysis, and the eigenfunction statistics using the Kullback–Leibler divergence and the inverse participation ratio, to diagnose the transition from regular to chaotic behavior. Numerically, we obtain the phase diagram of the regular and chaotic behavior on the parameter plane of many-body atomic interactions and synthetic gauge fields. Our results provide insight into the chaotic behavior of ultracold atoms with synthetic gauge fields and have potential applications in the quantum engineering of wave chaos.
I adopt a two-mode bosonic model with both strong atom–atom interaction and a periodic driven field to investigate the bias-modulated tunneling dynamics. I show that the quantum tunneling between two bosonic modes can be efficiently switched on/off when one continuously varies the amplitude of the driven field with an intermediate frequency. I explore the role of the atom–atom interaction on the switch effect as well. For the strong interaction case, in contrast to the unmodulated situation, there exists many windows in the atomic interaction domain for switching on/off the quantum tunneling. This result suggests a potential way to accurately control the quantum tunneling or coherent coupling of ultracold atoms in the strong interaction and self-trapping regimes.