Time-delayed collective dynamics in waveguide QED and bosonic quantum networks

ArXiv.org · 2025-05-05

This work introduces a theoretical framework to model the collective dynamics of quantum emitters in highly non-Markovian environments, interacting through the exchange of photons with significant retardations. The formalism consists on a set of coupled delay differential equations for the emitter's polarizations $σ^\pm_i$, supplemented by input-output relations that describe the field mediating the interactions. These equations capture the dynamics of both linear (bosonic) and nonlinear (two-level) emitter arrays. It is exact in some limits$-$e.g., bosonic emitters or generic systems with up to one collective excitation$-$and can be integrated to provide accurate results for larger numbers of photons. These equations support a study of collective spontaneous emission of emitter arrays in open waveguide-QED environments. This study uncovers an effect we term cascaded super- and sub-radiance, characterized by light-cone-limited propagation and increasingly correlated photon emission across distant emitters. The collective nature of this dynamics for two-level systems is evident both in the enhancement of collective emission rates, as well as in a superradiant burst with a faster than linear growth. While these effects should be observable in existing circuit QED devices or slight generalizations thereof, the formalism put forward in this work can be extended to model other systems such as network of quantum emitters or the generation of correlated photon states.

Enhanced Quantum Mpemba Effect with Squeezed Thermal Reservoirs

arXiv (Cornell University) · 2024-11-07

The phenomenon where a quantum system can be exponentially accelerated to its stationary state has been referred to as the Quantum Mpemba Effect (QMpE). Due to its analogy with the classical Mpemba effect, hot water freezes faster than cold water, this phenomenon has garnered significant attention. Although QMpE has been characterized and experimentally verified in different scenarios, the sufficient and necessary conditions to achieve such a phenomenon are still under investigation. In this paper, we address a sufficient condition for QMpE through a general approach for open quantum system dynamics. With the help of the Mpemba parameter introduced in this work to quantify how strong the QMpE can be, we discuss how our conditions can predict and explain the emergence of weak and strong QMpE in a robust way. As an application, by harnessing the intrinsic non-classical nature of squeezed thermal environments, we show how enhanced QMpE can be effectively induced when our conditions are met. We demonstrate that when the system interacts with thermal reservoirs, a hot qubit freezes faster than a cold qubit in the presence of squeezing. Our results provide tools and new insights, opening a broad avenue for further investigation at the most fundamental levels of this peculiar phenomenon in the quantum realm.

Scalable quantum eraser for superconducting integrated circuits

arXiv (Cornell University) · 2024-09-25

A fast and scalable scheme for multi-qubit resetting in superconducting quantum processors is proposed by exploiting the feasibility of frequency-tunable transmon qubits and transmon-like couplers to engineer a full programmable superconducting erasing head. The scalability of the device is verified by simultaneously resetting two qubits, where we show that collectivity effects may emerge as an fundamental ingredient to speed up the erasing process. Conversely, we also describe the appearance of decoherence-free subspace in multi-qubit chips, causing it to damage the device performance. To overcome this problem, a special set of parameters for the tunable frequency coupler is proposed, which allows us to erase even states within such subspace. To end, we offer a proposal to buildup integrated superconducting processors that can be efficiently connected to erasure heads in a scalable way.

EPIDEMIOLOGICAL PROFILE AND FREQUENCY OF DEPRESSIVE AND ANXIETY SYMPTOMS IN PATIENTS WITH GESTATIONAL TROPHOBLASTTIC DISEASE FOLLOWED AT THE REFERENCE CENTER OF PERNAMBUCO, BRAZIL: A CROSS-SECTIONAL STUDY

2022-10-20

Encoding quantum bits in bound electronic states of a graphene nanotorus

arXiv (Cornell University) · 2022 · 1 citations

• Computer Science
• Computer Science
• Physics

We propose to use the quantum states of an electron trapped on the inner surface of a graphene nanotorus to realize as a new kind of physical quantum bit, which can be used to encode quantum information. Fundamental tasks for quantum information processing, such as the qubit initialization and the implementation of arbitrary single qubit gates, can then be performed using external magnetic and electric fields. We also analyze the robustness of the device again systematic errors, which can be suppressed by a suitable choice of the external control fields. These findings open new prospects for the development an alternative platform for quantum computing, the scalability of which remains to be determined.

The testing for COVID-19 in symptomatic patients as a protective factor against stress, anxiety, and depression

Figshare · 2021-01-01

Abstract Objectives: to determine the frequency of stress, anxiety, and depression symptoms in symptomatic patients for COVID-19. To evaluate the associated factors involved in these variants. Methods: between May/June of 2020, it was conducted a prospective cross-section study with symptomatic participants for COVID-19 (n=300). It was applied an online questionnaire and the DASS-21 to evaluate the mental health of participants. Results: it was observed that 28.6%, 29.7% and 27% of the participants showed severe/extreme levels symptoms of stress, anxiety, and depression, respectively. The testing for COVID-19 application had constituted a protective factor for the development of psychiatric morbidity, once it had shown significant association in the low frequencies of severe/extreme depression [Odds Ratio (OR)]= 0.26; p=0.002) and stress (OR=0.39; p=0.01). Conclusion: individuals that are symptomatic for COVID-19 are a vulnerable group that may present high symptomatology for depression, anxiety, and stress. The identification of psychiatric morbidity frequency and its associated factors may contribute for the development of mental health strategies aiming at the prevention and mitigation of psychological impact in COVID-19 symptomatic population during the pandemic.

Perfil epidemiológico das pacientes com doença trofoblástica gestacional acompanhadas no Centro de Referência do Recife

2021-01-01

Perfil clínico e epidemiológico das mulheres atendidas no setor de reprodução humana do IMIP: estudo de corte transversal

2021-01-01

The testing for COVID-19 in symptomatic patients as a protective factor against stress, anxiety, and depression/ Testagem para a COVID-19 em pacientes sintomáticos como fator protetivo contra estresse, ansiedade e depressão

2021-01-01

Abstract Objectives: to determine the frequency of stress, anxiety, and depression symptoms in symptomatic patients for COVID-19. To evaluate the associated factors involved in these variants. Methods: between May/June of 2020, it was conducted a prospective cross-section study with symptomatic participants for COVID-19 (n=300). It was applied an online questionnaire and the DASS-21 to evaluate the mental health of participants. Results: it was observed that 28.6%, 29.7% and 27% of the participants showed severe/extreme levels symptoms of stress, anxiety, and depression, respectively. The testing for COVID-19 application had constituted a protective factor for the development of psychiatric morbidity, once it had shown significant association in the low frequencies of severe/extreme depression [Odds Ratio (OR)]= 0.26; p=0.002) and stress (OR=0.39; p=0.01). Conclusion: individuals that are symptomatic for COVID-19 are a vulnerable group that may present high symptomatology for depression, anxiety, and stress. The identification of psychiatric morbidity frequency and its associated factors may contribute for the development of mental health strategies aiming at the prevention and mitigation of psychological impact in COVID-19 symptomatic population during the pandemic.

Generating long-lived entangled states with free-space collective spontaneous emission

arXiv (Cornell University) · 2021-10-28 · 1 citations

Considering the paradigmatic case of a cloud of two-level atoms interacting through common vacuum modes, we show how cooperative spontaneous emission, which is at the origin of superradiance, leads the system to long-lived entangled states at late times. These subradiant modes are characterized by an entanglement between all particles, independently of their geometrical configuration. While there is no threshold on the interaction strength necessary to entangle all particles, stronger interactions lead to longer-lived entanglement.