17,867 research outputs found
Floquet engineering of long-range p-wave superconductivity: Beyond the high-frequency limit
It has been shown that long-range {\it p}-wave superconductivity in a Kitaev
chain can be engineered via an ac field with a high frequency [Benito et al.,
Phys. Rev. B 90, 205127 (2014)]. For its experimental realization, however,
theoretical understanding of Floquet engineering with a broader range of
driving frequencies becomes important. In this work, focusing on the ac-driven
tunneling interactions of a Kitaev chain, we investigate effects from the
leading correction to the high-frequency limit on the emergent {\it p}-wave
superconductivity. Importantly, we find new engineered long-range {\it p}-wave
pairing interactions that can significantly alter the ones in the
high-frequency limit at long interaction ranges. We also find that the leading
correction additionally generates nearest-neighbor {\it p}-wave pairing
interactions with a renormalized pairing energy, long-range tunneling
interactions, and in particular multiple pairs of Floquet Majorana edge states
that are destroyed in the high- frequency limit.Comment: 13 pages, 8 figure
Collective quantum phase slips in multiple nanowire junctions
Realization of robust coherent quantum phase slips represents a significant
experimental challenge. Here we propose a new design consisting of multiple
nanowire junctions to realize a phase-slip flux qubit. It admits good
tunability provided by gate voltages applied on superconducting islands
separating nanowire junctions. In addition, the gates and junctions can be
identical or distinct to each other leading to symmetric and asymmetric setups.
We find that the asymmetry can improve the performance of the proposed device,
compared with the symmetric case. In particular, it can enhance the effective
rate of collective quantum phase slips. Furthermore, we demonstrate how to
couple two such devices via a mutual inductance. This is potentially useful for
quantum gate operations. Our investigation on how symmetry in multiple nanowire
junctions affects the device performance should be useful for the application
of phase-slip flux qubits in quantum information processing and quantum
metrology.Comment: 12 pages, 6 figure
Cooling a nanomechanical resonator by a triple quantum dot
We propose an approach for achieving ground-state cooling of a nanomechanical
resonator (NAMR) capacitively coupled to a triple quantum dot (TQD). This TQD
is an electronic analog of a three-level atom in configuration which
allows an electron to enter it via lower-energy states and to exit only from a
higher-energy state. By tuning the degeneracy of the two lower-energy states in
the TQD, an electron can be trapped in a dark state caused by destructive
quantum interference between the two tunneling pathways to the higher-energy
state. Therefore, ground-state cooling of an NAMR can be achieved when
electrons absorb readily and repeatedly energy quanta from the NAMR for
excitations.Comment: 6 pages, 3 figure
Morphology and thermal conductivity of model organic aerogels
The intersection volume of two independent 2-level cut Gaussian random fields
is proposed to model the open-cell microstructure of organic aerogels. The
experimentally measured X-ray scattering intensity, surface area and solid
thermal conductivity of both polymeric and colloidal organic aerogels can be
accounted for by the model.Comment: 5 pages. RevTex with 4 encapsulated figures. Higher resolution
figures have been submitted for publication. To be published in Phys. Rev. E
(Rapid Comm.). email, [email protected]
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