1,433 research outputs found
Mentoring Meetings Increase Student Performance on “High Stakes” Projects in STEM
The current project addresses whether one-on-one, mentoring meetings to discuss poster rough drafts will impact learning more consistently.https://digitalscholarship.unlv.edu/btp_expo/1070/thumbnail.jp
Optimal operating conditions of an entangling two-transmon gate
We identify optimal operating conditions of an entangling two-qubit gate
realized by a capacitive coupling of two superconducting charge qubits in a
transmission line resonator (the so called "transmons"). We demonstrate that
the sensitivity of the optimized gate to 1/f flux and critical current noise is
suppressed to leading order. The procedure only requires a preliminary estimate
of the 1/f noise amplitudes. No additional control or bias line beyond those
used for the manipulation of individual qubits are needed. The proposed
optimization is effective also in the presence of relaxation processes and of
spontaneous emission through the resonator (Purcell effect).Comment: 12 pages, 5 figure
Dynamical suppression of telegraph and 1/f noise due to quantum bistable fluctuator
We study dynamical decoupling of a qubit from non gaussian quantum noise due
to discrete sources, as bistable fluctuators and 1/f noise. We obtain analytic
and numerical results for generic operating point. For very large pulse
frequency, where dynamic decoupling compensates decoherence, we found universal
behavior. At intermediate frequencies noise can be compensated or enhanced,
depending on the nature of the fluctuators and on the operating point. Our
technique can be applied to a larger class of non-gaussian environments.Comment: Revtex 4, 5 pages, 3 figures. Title revised and some other minor
changed. Final version as published in PR
Decoherence due to telegraph and 1/f noise in Josephson qubits
We study decoherence due to random telegraph and 1/f noise in Josephson
qubits. We illustrate differences between gaussian and non gaussian effects at
different working points and for different protocols. Features of the
intrinsically non-gaussian and non-Markovian low-frequency noise may explain
the rich physics observed in the spectroscopy and the dynamics of charge based
devices.Comment: 6 pages, 4 figures. Proceedings of the International Symposium on
Mesoscopic Superconductivity and Spintronics 2004 (MS+S2004), Atsugi, Japa
Broadband noise decoherence in solid-state complex architectures
Broadband noise represents a severe limitation towards the implementation of
a solid-state quantum information processor. Considering common spectral forms,
we propose a classification of noise sources based on the effects produced
instead of on their microscopic origin. We illustrate a multi-stage approach to
broadband noise which systematically includes only the relevant information on
the environment, out of the huge parametrization needed for a microscopic
description. We apply this technique to a solid-state two-qubit gate in a fixed
coupling implementation scheme.Comment: Proceedings of Nobel Symposium 141: Qubits for Future Quantum
Informatio
Decoherence due to discrete noise in Josephson qubits
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 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 needed to characterize the effect of the
environment. Although in general information beyond the power spectrum is
needed, in many situations this results in the knowledge of only one more
microscopic parameter of the environment. This allows to determine which
degrees of freedom of the environment are effective sources of decoherence in
each different physical situation considered.Comment: 20 pages, 11 figure
Design of a Lambda system for population transfer in superconducting nanocircuits
The implementation of a Lambda scheme in superconducting artificial atoms
could allow detec- tion of stimulated Raman adiabatic passage (STIRAP) and
other quantum manipulations in the microwave regime. However symmetries which
on one hand protect the system against decoherence, yield selection rules which
may cancel coupling to the pump external drive. The tradeoff between efficient
coupling and decoherence due to broad-band colored Noise (BBCN), which is often
the main source of decoherence is addressed, in the class of nanodevices based
on the Cooper pair box (CPB) design. We study transfer efficiency by STIRAP,
showing that substantial efficiency is achieved for off-symmetric bias only in
the charge-phase regime. We find a number of results uniquely due to
non-Markovianity of BBCN, namely: (a) the efficiency for STIRAP depends
essentially on noise channels in the trapped subspace; (b) low-frequency
fluctuations can be analyzed and represented as fictitious correlated
fluctuations of the detunings of the external drives; (c) a simple figure of
merit for design and operating prescriptions allowing the observation of STIRAP
is proposed. The emerging physical picture also applies to other classes of
coherent nanodevices subject to BBCN.Comment: 14 pages, 11 figure
Hidden entanglement, system-environment information flow and non-Markovianity
It is known that entanglement dynamics of two noninteracting qubits, locally
subjected to classical environments, may exhibit revivals. A simple explanation
of this phenomenon may be provided by using the concept of hidden entanglement,
which signals the presence of entanglement that may be recovered without the
help of nonlocal operations. Here we discuss the link between hidden
entanglement and the (non-Markovian) flow of classical information between the
system and the environment.Comment: 9 pages, 2 figures; proceedings of the conference IQIS 2013,
September 24-26 2013, Como, Ital
- …