Control of tunneling in an atomtronic switching device

The precise control of quantum systems will play a major role in the realization of atomtronic devices. As in the case of electronic systems, a desirable property is the ability to implement switching. Here we show how to implement switching in a model of dipolar bosons confined to three coupled wells. The model describes interactions between bosons, tunneling of bosons between adjacent wells, and the effect of an external field. We conduct a study of the quantum dynamics of the system to probe the conditions under which switching behavior can occur. The analysis considers both integrable and non-integrable regimes within the model. Through variation of the external field, we demonstrate how the system can be controlled between various switched-on and switched-off configurations.Comment: Revised Communications Physics (open access) version; Major revision: 8 pages, 6 figures; Supplementary material: 2 pages, 5 figure

Interacting bosons in a triple well : preface of many-body quantum chaos

Systems of interacting bosons in triple-well potentials are of significant theoretical and experimental interest. They are explored in contexts that range from quantum phase transitions and quantum dynamics to semiclassical analysis. Here, we systematically investigate the onset of quantum chaos in a triple-well model that moves away from integrability as its potential gets tilted. Even in its deepest chaotic regime, the system presents features reminiscent of integrability. Our studies are based on level spacing distribution and spectral form factor, structure of the eigenstates, and diagonal and off-diagonal elements of observables in relationship to the eigenstate thermalization hypothesis. With only three sites, the system’s eigenstates are at the brink of becoming fully chaotic, so they do not yet exhibit Gaussian distributions, which resonates with the results for the observables

Control of tunneling in an atomtronic switching device

The precise control of quantum systems will play a major role in the realization of atomtronic devices. As in the case of electronic systems, a desirable property is the ability to implement switching. Here we show how to implement switching in a model of dipolar bosons con fi ned to three coupled wells. The model describes interactions between bosons, tunneling of bosons between adjacent wells, and the effect of an external fi eld. We conduct a study of the quantum dynamics of the system to probe the conditions under which switching behavior can occur. The analysis considers both integrable and non-integrable regimes within the model. Through variation of the external fi eld, we demonstrate how the system can be controlled between various “ switched-on ” and “ switched-off ” configurations

Integrable atomtronic interferometry

High sensitivity quantum interferometry requires more than just access to entangled states. It is achieved through deep understanding of quantum correlations in a system. Integrable models offer the framework to develop this understanding. We communicate the design of interferometric protocols for an integrable model that describes the interaction of bosons in a four-site configuration. Analytic formulae for the quantum dynamics of certain observables are computed. These expose the system's functionality as both an interferometric identifier, and producer, of NOON states. Being equivalent to a controlled-phase gate acting on two hybrid qudits, this system also highlights an equivalence between Heisenberg-limited interferometry and quantum information. These results are expected to open new avenues for integrability-enhanced atomtronic technologies.Comment: 6 pages, 4 figures, 1 tabl

Protocol designs for NOON states

The ability to reliably prepare non-classical states will play a major role in the realization of quantum technology. NOON states, belonging to the class of Schrödinger cat states, have emerged as a leading candidate for several applications. Here we show how to generate NOON states in a model of dipolar bosons confined to a closed circuit of four sites. This is achieved by designing protocols to transform initial Fock states to NOON states through use of time evolution, application of an external field, and local projective measurements. The evolution time is independent of total particle number, offering an encouraging prospect for scalability. By variation of the external field strength, we demonstrate how the system can be controlled to encode a phase into a NOON state. We also discuss the physical feasibility, via ultracold dipolar atoms in an optical superlattice setup. Our proposal showcases the benefits of quantum integrable systems in the design of protocols

Integrabilidade no projeto e no controle de dispositivos quânticos

The precise control of quantum systems will play an important role in the realization of atomtronic devices. In this thesis, we show how to explore the concept of integrability to guide the design of ultracold atom devices with potential application in emerging quantum technologies. Starting from a family of integrable multi-well Hamiltonians, which describe interactions between dipolar bosons and tunneling of bosons between adjacent wells, we investigate and find physical applications for the three and the four well cases. Initially, we conduct a study of the quantum dynamics of the triple-well system to probe the conditions under which a switching behavior can occur. Through variation of the external field, we demonstrate how the system can be controlled between various “switched-on” and “switched-off” configurations. In addition, we investigate the generation of entangled states in this model for a large range of Fock initial states. In sequence, we study the four-well model, communicating the design of interferometric protocols through analytic formulae. These expose the system as an interferometric identifier and producer of NOON states (entangled state related to the Schrödinger cat state). Then, we design two protocols, one probabilistic and another deterministic, to transform initial Fock states into NOON states, enabling phase encoding with high fidelity. The physical feasibility of both devices is also discussed via ultracold dipolar atoms trapped in optical setups. Since these physical setups could, in principle, be utilized in other resources, we also make a preliminary discussion of the onset of quantum chaos in the triple-well model.O controle preciso de sistemas quânticos desempenhará um papel importante na realização de dispositivos atomtrônicos. Nesta tese, mostramos como explorar o conceito de integrabilidade para orientar o projeto de dispositivos de átomos ultrafrios com potencial aplicação em tecnologias quânticas emergentes. Partindo de uma família de hamiltonianos multi-poços integráveis, que descrevem interações entre bósons dipolares e tunelamento de bósons entre poços adjacentes, escolhemos os casos de três e quatro poços para explorar possíıveis aplicações fíısicas. Inicialmente, realizamos um estudo da dinâmica quântica do sistema de poço triplo para investigar as condições sob as quais um comportamento do tipo transistor pode ocorrer. Através da variação de um campo externo, demonstramos como o sistema pode ser controlado entre várias configurações de “ligado” e “desligado”, simulando um switching device. Além disso, investigamos a capacidade do sistema em gerar estados emaranhados através de sua evolução temporal, para uma grande variedade de estados iniciais de Fock. Na sequência, estudamos o modelo de quatro poços, comunicando o projeto de protocolos interferométricos por meio de expressões analíticas. Estes expõem o sistema como um identificador interferométrico e produtor de estados NOON (estado emaranhado relacionado ao estado do gato de Schrödinger). Em seguida, projetamos dois protocolos, um probabilístico e outro determinístico, para transformar estados iniciais de Fock em estados NOON, indicando como codificar fases com alta fidelidade. A viabilidade física de ambos dispositivos é discutida através de átomos dipolares ultrafrios aprisionados em configurações ópticas. Como essas configurações físicas podem, em princípio, ser utilizadas para investigar outros fenômenos quânticos, também apresentamos uma discussão preliminar sobre o prefácio do caos quântico no modelo de poço triplo