Search results for: G. Falci

Items from 1 to 20 out of 23 results

article

Photon pair production by STIRAP in ultrastrongly coupled matter-radiation systems

A. Ridolfo, G. Falci, F. M. D. Pellegrino, G. D. Maccarrone, more

The European Physical Journal Special Topics > 2019 > 227 > 15-16 > 2183-2188

Artificial atoms (AAs) offer the possibility to design physical systems implementing new regimes of ultrastrong coupling (USC) between radiation and matter [C. Ciuti et al., Phys. Rev. B 72, 115303 (2005)], where previously unexplored non-perturbative physics emerges. While experiments so far provided only spectroscopic evidence of USC, we propose the dynamical detection of virtual photon pairs in...

article

Quantum Zeno and anti-Zeno effect on a two-qubit gate by dynamical decoupling

A. D’Arrigo, G. Falci, E. Paladino

The European Physical Journal Special Topics > 2019 > 227 > 15-16 > 2189-2194

Controlling the dynamics of entanglement and preventing its disappearance are central requisites for any implementation of quantum information processing. Many solid state qubits are affected by non-Markovian noise, often with 1/f spectrum. Leading order dephasing effects are captured by treating noise in the quasistatic approximation. In this article we investigate dynamical decoupling of a two-qubit...

chapter

Decoherence Due to Discrete Noise in Josephson Qubits

E. Paladino, L. Faoro, G. Falci

Advances in Solid State Physics > Advances in Solid State Physics > 747-762

We study decoherence produced by a discrete environment on a charge Josephson qubit by introducing a model of an environment of bistable fluctuators. In particular we address the effect of 1/f noise where memory effects play an important role. We perform a detailed investigation of various computation procedures (single shot measurements, repeated measurements) and discuss the problem of the information...

chapter

Semiclassical Analysis of 1/fNoise in Josephson Qubits

E. Paladino, L. Faoro, A. D’Arrigo, G. Falci

Quantum Computing and Quantum Bits in Mesoscopic Systems > 237-245

Recent progress in the development of nanoscale electronic devices has enhanced the interest in the problem of 1/f noise. Numerous experiments have shown that the performance of single electron tunneling (SET) devices strongly suffer from offset charge fluctuations responsible for the observed 1/f charge noise [1]. Moreover it has been realized that such a noise plays a significant role in determining...

article

Recovering entanglement by local operations

A. D’Arrigo, R. Lo Franco, G. Benenti, E. Paladino, more

Annals of Physics > 2014 > 350 > Complete > 211-224

We investigate the phenomenon of bipartite entanglement revivals under purely local operations in systems subject to local and independent classical noise sources. We explain this apparent paradox in the physical ensemble description of the system state by introducing the concept of “hidden” entanglement, which indicates the amount of entanglement that cannot be exploited due to the lack of classical...

article

Transmission of classical and quantum information through a quantum memory channel with damping

A. D’Arrigo, G. Benenti, G. Falci

The European Physical Journal D > 2012 > 66 > 6 > 1-15

We consider the transfer of classical and quantum information through a memory amplitude damping channel. Such a quantum channel is modeled as a damped harmonic oscillator, the interaction between the information carriers — a train of qubits — and the oscillator being of the Jaynes-Cummings kind. We prove that this memory channel is forgetful, so that quantum coding theorems hold for its capacities...

article

Dynamics of Weyl wave-packets in a noisy environment

G. Falci, M. Morello Baganella, M. Berritta, A. D’Arrigo, more

Physica E: Low-dimensional Systems and Nanostructures > 2010 > 42 > 3 > 584-589

We study the effect of coupling to an environment a particle whose dynamics is governed by the Weyl equation. This model describes chiral quasi-particles in graphene in the presence of noise. Using an exact mapping of the Hamiltonian onto a conditional spin–boson model we study the dynamics of wave-packets, and how the phenomena of spin-separation and Zitterbewegung survive in the presence of noise...

article

Relaxation processes in solid-state two-qubit gates

E. Paladino, A. D’Arrigo, A. Mastellone, G. Falci

Physica E: Low-dimensional Systems and Nanostructures > 2010 > 42 > 3 > 439-443

We consider a solid-state two-qubit gate subject to relaxation processes originated by transverse and longitudinal fluctuations of the single-qubit Hamiltonians. We model each noise component as a bosonic bath characterized by a specific power spectrum. We specialize our analysis to a i-SWAP gate implemented by Josephson qubits in a fixed coupling scheme. For high-frequency noise spectra extrapolated...

article

Memory effects in quantum information transmission across a Hamiltonian dephasing channel

A. D'Arrigo, G. Benenti, G. Falci

The European Physical Journal Special Topics > 2008 > 160 > 1 > 83-94

. We study a dephasing channel with memory, modelled by a multimode environment of oscillators. Focusing on the case of two channel uses, we show that memory effects can enhance the amount of coherent quantum information transmitted down the channel. We also propose a coding-decoding scheme that takes advantage of memory to improve the fidelity of transmission.

article

Sensitivity to parameters of STIRAP in a Cooper Pair Box

G. Mangano, J. Siewert, G. Falci

The European Physical Journal Special Topics > 2008 > 160 > 1 > 259-268

. The rapid experimental progress in the field of superconducting nanocircuits gives rise to an increasing quest for advanced quantum-control techniques for these macroscopically coherent systems. Here we demonstrate theoretically that stimulated Raman adiabatic passage (STIRAP), a well-established method in quantum optics, should be possible with the quantronium setup of a Cooper-pair box. We find...

article

Coupled Josephson qubits: Characterization of low-frequency charge noise

A. Mastellone, A. D'Arrigo, E. Paladino, G. Falci

The European Physical Journal Special Topics > 2008 > 160 > 1 > 291-300

. The realization of coupled qubit setups is a fundamental step towards implementation of universal quantum computing architectures. Solid state nano- devices, despite being very promising from the point of view of scalability and integration, strongly suffer from various noise sources. Particular detrimental role is played by low-frequency noise components. Here we identify stability conditions against...

article

Structured environments in solid state systems: Crossover from Gaussian to non-Gaussian behavior

E. Paladino, A.G. Maugeri, M. Sassetti, G. Falci, more

Physica E: Low-dimensional Systems and Nanostructures > 2007 > 40 > 1 > 198-205

The variety of noise sources typical of the solid state represents the main limitation toward the realization of controllable and reliable quantum nanocircuits, as those allowing quantum computation. Such “structured environments” are characterized by a non-monotonous noise spectrum sometimes showing resonances at selected frequencies. Here we focus on a prototype structured environment model: a two-state...

article

Pure dephasing due to damped bistable quantum impurities

E. Paladino, M. Sassetti, G. Falci, U. Weiss

Chemical Physics > 2006 > 322 > 1-2 > 98-107

We study the dynamics of a spin (qubit) coupled to a bistable quantum impurity interacting with a Gaussian bath modeled by a ohmic spin boson model. For white noise the complete dynamics in the four-dimensional Hilbert space is analyzed within a Lindblad formalism. For ohmic damping at finite temperatures we resort to a functional integral approach. We show how different dynamical regimes and crossover...

article

Low-Frequency Noise Characterization in Charge-Based Coherent Nanodevices

G. Falci, A. Mastellone, A. D’Arrigo, E. Paladino

Open Systems & Information Dynamics > 2006 > 13 > 3 > 323-332

Low-frequency noise has been recognized as the main mechanism of decoherence in present-day solid state coherent nanodevices. Often low-frequency noise has a 1/f spectrum, thus the responsible degrees of freedom are almost static during the coherent time evolution of the device. Their effect is to reduce the amplitude of the measured signal by an effect analogous to inhomogeneous broadening in NMR...

article

Quantum control of discrete noise in Josephson qubits

A. D’Arrigo, G. Falci, A. Mastellone, E. Paladino

Physica E: Low-dimensional Systems and Nanostructures > 2005 > 29 > 1-2 > 297-307

We develop a technique to study dynamical decoupling of a quantum system from a structured environment and apply it to non-Gaussian noise due to quantum bistable fluctuators and 1/f noise. We obtain analytic and numerical results for general operating points. For very large pulse frequency dynamic decoupling compensates decoherence and we found universal behavior. At intermediate frequencies noise...

article

Modulation of dephasing due to a spin-boson environment

E. Paladino, M. Sassetti, G. Falci

Chemical Physics > 2004 > 296 > 2-3 > 325-332

We study the reduced dynamics of a spin (qubit) coupled to a spin-boson environment in the case of pure dephasing. We derive formal exact expressions which can be cast in terms of exact integro-differential master equations. We present results for a SB environment with ohmic dissipation at finite temperatures. For the special value of the ohmic damping strength K=1/2, the reduced dynamics is found...

article

Thermodynamics in disordered metallic dots

G. Falci, Rosario Fazio, A. Fubini, A. Mastellone

Current Applied Physics > 2003 > 3 > 5 > 445-447

A general discussion on the signature of the pairing correlations in the behavior of the thermodynamical observables is presented.

article

Universal features in ensembles of small superconducting grains

G. Falci, A. Fubini, A. Mastellone, Rosario Fazio

Physica E: Low-dimensional Systems and Nanostructures > 2003 > 18 > 1-3 > 31-32

The physical properties of an ensemble of disordered ultra-small superconducting grains are analyzed by means of a simple Hamiltonian. We find that both the thermodynamical observables and the interplay between the pairing and exchange interactions display universal features.

article

Decoherence and 1/f noise in Josephson qubits

E. Paladino, L. Faoro, A. D'Arrigo, G. Falci

Physica E: Low-dimensional Systems and Nanostructures > 2003 > 18 > 1-3 > 29-30

We analyse decoherence in Josephson qubits induced by background charges responsible for 1/f noise. To this end we introduce a quantum mechanical model of a discrete environment. The discrete nature of the environment leads to a number of new features which are mostly pronounced for slowly moving charges.

article

Josephson nanocircuit in the presence of linear quantum noise

E. Paladino, F. Taddei, G. Giaquinta, G. Falci

Physica E: Low-dimensional Systems and Nanostructures > 2003 > 18 > 1-3 > 39-40

We derive the effective hamiltonian for a charge-Josephson qubit in a circuit with no use of phenomenological arguments, showing how energy renormalizations induced by the environment appear with no need of phenomenological counterterms. This analysis may be important for multiqubit systems and geometric quantum computation.

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Search results for: G. Falci

Photon pair production by STIRAP in ultrastrongly coupled matter-radiation systems

Quantum Zeno and anti-Zeno effect on a two-qubit gate by dynamical decoupling

Decoherence Due to Discrete Noise in Josephson Qubits

Semiclassical Analysis of 1/fNoise in Josephson Qubits

Recovering entanglement by local operations

Transmission of classical and quantum information through a quantum memory channel with damping

Dynamics of Weyl wave-packets in a noisy environment

Relaxation processes in solid-state two-qubit gates

Memory effects in quantum information transmission across a Hamiltonian dephasing channel

Sensitivity to parameters of STIRAP in a Cooper Pair Box

Coupled Josephson qubits: Characterization of low-frequency charge noise

Structured environments in solid state systems: Crossover from Gaussian to non-Gaussian behavior

Pure dephasing due to damped bistable quantum impurities

Low-Frequency Noise Characterization in Charge-Based Coherent Nanodevices

Quantum control of discrete noise in Josephson qubits

Modulation of dephasing due to a spin-boson environment

Thermodynamics in disordered metallic dots

Universal features in ensembles of small superconducting grains

Decoherence and 1/f noise in Josephson qubits

Josephson nanocircuit in the presence of linear quantum noise

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