1,122 research outputs found
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
Basic protocols in quantum reinforcement learning with superconducting circuits
Superconducting circuit technologies have recently achieved quantum protocols
involving closed feedback loops. Quantum artificial intelligence and quantum
machine learning are emerging fields inside quantum technologies which may
enable quantum devices to acquire information from the outer world and improve
themselves via a learning process. Here we propose the implementation of basic
protocols in quantum reinforcement learning, with superconducting circuits
employing feedback-loop control. We introduce diverse scenarios for
proof-of-principle experiments with state-of-the-art superconducting circuit
technologies and analyze their feasibility in presence of imperfections. The
field of quantum artificial intelligence implemented with superconducting
circuits paves the way for enhanced quantum control and quantum computation
protocols.Comment: Published versio
Quantum Memristors in Quantum Photonics
We propose a method to build quantum memristors in quantum photonic
platforms. We firstly design an effective beam splitter, which is tunable in
real-time, by means of a Mach-Zehnder-type array with two equal 50:50 beam
splitters and a tunable retarder, which allows us to control its reflectivity.
Then, we show that this tunable beam splitter, when equipped with weak
measurements and classical feedback, behaves as a quantum memristor. Indeed, in
order to prove its quantumness, we show how to codify quantum information in
the coherent beams. Moreover, we estimate the memory capability of the quantum
memristor. Finally, we show the feasibility of the proposed setup in integrated
quantum photonics
Developments in entanglement theory and applications to relevant physical systems
This Thesis is devoted to the analysis of entanglement in relevant physical
systems. Entanglement is the conducting theme of this research, though I do not
dedicate to a single topic, but consider a wide scope of physical situations. I
have followed mainly three lines of research for this Thesis, with a series of
different works each, which are, Entanglement and Relativistic Quantum Theory,
Continuous-variable entanglement, and Multipartite entanglement.Comment: Ph.D. Thesis, April 2007, Universidad Autonoma de Madri
Efficient quantum simulation of fermionic and bosonic models in trapped ions
We analyze the efficiency of quantum simulations of fermionic and bosonic
models in trapped ions. In particular, we study the optimal time of entangling
gates and the required number of total elementary gates. Furthermore, we
exemplify these estimations in the light of quantum simulations of quantum
field theories, condensed-matter physics, and quantum chemistry. Finally, we
show that trapped-ion technologies are a suitable platform for implementing
quantum simulations involving interacting fermionic and bosonic modes, paving
the way for overcoming classical computers in the near future.Comment: 13 pages, 3 figures. Published in EPJ Quantum Technolog
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