353 research outputs found
Semiclassical Dynamics from Zeno-Like measurements
The usual semiclassical approximation for atom-field dynamics consists in
substituting the field operators by complex numbers related to the (supposedly
large enough) intensity of the field. We show that a semiclassical evolution
for coupled systems can always be obtained by frequent Zeno-like measurements
on the state of one subsystems, independently of the field intensity in the
example given. We study the Jaynes Cummings model from this perspective
Effects of Markovian noise and cavity disorders on the entanglement dynamics of double Jaynes-Cummings models
Dynamics of double Jaynes-Cummings models are studied in the presence of
Markovian noise and cavity disorders with specific attention to entanglement
sudden death and revivals. The study is focused on the glassy disorders, which
remain unchanged during the observations. The field is initially assumed to be
in a vacuum state, while the atoms are considered to be in a specific two-qubit
superposition state. Specifically, the study has revealed that the presence of
noise, or a nonlinear pump results in interesting behaviors in the entanglement
dynamics. Further, entanglement sudden death is observed in the presence of
Markovian noise and nonlinear pump. The presence of entanglement sudden deaths
and revivals have also been observed in cases where they were absent initially
for the chosen states. The effect of noise on the dynamics of the system is to
decay the characteristics, while that of the disorder is to wash them out. On
the other hand, the introduction of nonlinearity is found to cause the dynamics
of the system to speed up.Comment: Entanglement dynamics of variants of double Jaynes-Cummings models
are studie
From Quantum Optics to Quantum Technologies
Quantum optics is the study of the intrinsically quantum properties of light.
During the second part of the 20th century experimental and theoretical
progress developed together; nowadays quantum optics provides a testbed of many
fundamental aspects of quantum mechanics such as coherence and quantum
entanglement. Quantum optics helped trigger, both directly and indirectly, the
birth of quantum technologies, whose aim is to harness non-classical quantum
effects in applications from quantum key distribution to quantum computing.
Quantum light remains at the heart of many of the most promising and
potentially transformative quantum technologies. In this review, we celebrate
the work of Sir Peter Knight and present an overview of the development of
quantum optics and its impact on quantum technologies research. We describe the
core theoretical tools developed to express and study the quantum properties of
light, the key experimental approaches used to control, manipulate and measure
such properties and their application in quantum simulation, and quantum
computing.Comment: 20 pages, 3 figures, Accepted, Prog. Quant. Ele
Quantum state engineering in hybrid open quantum systems
We investigate a possibility to generate nonclassical states in light-matter coupled noisy quantum systems, namely, the anisotropic Rabi and Dicke models. In these hybrid quantum systems, a competing influence of coherent internal dynamics and environment-induced dissipation drives the system into nonequilibrium steady states (NESSs). Explicitly, for the anisotropic Rabi model, the steady state is given by an incoherent mixture of two states of opposite parities, but as each parity state displays light-matter entanglement, we also find that the full state is entangled. Furthermore, as a natural extension of the anisotropic Rabi model to an infinite spin subsystem, we next explored the NESS of the anisotropic Dicke model. The NESS of this linearized Dicke model is also an inseparable state of light and matter. With an aim to enrich the dynamics beyond the sustainable entanglement found for the NESS of these hybrid quantum systems, we also propose to combine an all-optical feedback strategy for quantum state protection and for establishing quantum control in these systems. Our present work further elucidates the relevance of such hybrid open quantum systems for potential applications in quantum architectures
Digital-analog quantum simulation of generalized Dicke models with superconducting circuits
We propose a digital-analog quantum simulation of generalized Dicke models
with superconducting circuits, including Fermi-Bose condensates, biased and
pulsed Dicke models, for all regimes of light-matter coupling. We encode these
classes of problems in a set of superconducting qubits coupled with a bosonic
mode implemented by a transmission line resonator. Via digital-analog
techniques, an efficient quantum simulation can be performed in
state-of-the-art circuit quantum electrodynamics platforms, by suitable
decomposition into analog qubit-bosonic blocks and collective single-qubit
pulses through digital steps. Moreover, just a single global analog block would
be needed during the whole protocol in most of the cases, superimposed with
fast periodic pulses to rotate and detune the qubits. Therefore, a large number
of digital steps may be attained with this approach, providing a reduced
digital error. Additionally, the number of gates per digital step does not grow
with the number of qubits, rendering the simulation efficient. This strategy
paves the way for the scalable digital-analog quantum simulation of many-body
dynamics involving bosonic modes and spin degrees of freedom with
superconducting circuits.Comment: Published version, with added reference
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