98 research outputs found
The single electron R-pump: first experiment
We fabricated and tested the single electron R-pump, i.e. a three-junction Al
circuit with on-chip Cr resistors. We show that due to the presence of the
resistors (R > h/e^2 = 25.8 kOhm), the accuracy of electron transfer in the
R-pump can approach the level of 10^-8. Preliminary results of experiment with
the R-pump made at PTB are reported.Comment: 2 pages, incl. 3 figure
Relativity principles in 1+1 dimensions and differential aging reversal
We study the behavior of clocks in 1+1 spacetime assuming the relativity
principle, the principle of constancy of the speed of light and the clock
hypothesis. These requirements are satisfied by a class of Finslerian theories
parametrized by a real coefficient , special relativity being recovered
for . The effect of differential aging is studied for the different
values of . Below the critical values the differential
aging has the usual direction - after a round trip the accelerated observer
returns younger than the twin at rest in the inertial frame - while above the
critical values the differential aging changes sign. The non-relativistic case
is treated by introducing a formal analogy with thermodynamics.Comment: 12 pages, no figures. Previous title "Parity violating terms in
clocks' behavior and differential aging reversal". v2: shortened
introduction, some sections removed, pointed out the relation with Finsler
metrics. Submitted to Found. Phys. Let
Cooper pair cotunneling in single charge transistors with dissipative electromagnetic environment
We observed current-voltage characteristics of superconducting single charge
transistors with on-chip resistors of R about R_Q = h/4e^2 = 6.45 kOhm, which
are explained in terms of Cooper-pair cotunneling. Both the effective strength
of Josephson coupling and the cotunneling current are modulated by the
gate-induced charge on the transistor island. For increasing values of the
resistance R we found the Cooper pair current at small transport voltages to be
dramatically suppressed.Comment: 4 pages and 2 figure
Ground-state characterization of Nb charge-phase Josephson qubits
We present investigations of Josephson charge-phase qubits inductively
coupled to a radio-frequency driven tank-circuit enabling the readout of the
states by measuring the Josephson inductance of the qubit. The circuits
including junctions with linear dimensions of 60 nm and 80 nm are fabricated
from Nb trilayer and allowing the determination of relevant sample parameters
at liquid helium temperature. The observed partial suppression of the
circulating supercurrent at 4.2 K is explained in the framework of a quantum
statistical model. We have probed the ground-state properties of qubit
structures with different ratios of the Josephson coupling to Coulomb charging
energy at 20 mK, demonstrating both the magnetic control of phase and the
electrostatic control of charge on the qubit island.Comment: 8 pages, 8 figure
Rf-induced transport of Cooper pairs in superconducting single electron transistors in a dissipative environment
We investigate low-temperature and low-voltage-bias charge transport in a
superconducting Al single electron transistor in a dissipating environment,
realized as on-chip high-ohmic Cr microstrips. In our samples with relatively
large charging energy values Ec > EJ, where EJ is the energy of the Josephson
coupling, two transport mechanisms were found to be dominating, both based on
discrete tunneling of individual Cooper pairs: Depending on the gate voltage
Vg, either sequential tunneling of pairs via the transistor island (in the open
state of the transistor around the points Qg = CgVg = e mod(2e), where Cg is
the gate capacitance) or their cotunneling through the transistor (for Qg away
of these points) was found to prevail in the net current. As the open states of
our transistors had been found to be unstable with respect to quasiparticle
poisoning, high-frequency gate cycling (at f ~ 1 MHz) was applied to study the
sequential tunneling mechanism. A simple model based on the master equation was
found to be in a good agreement with the experimental data.Comment: 8 pages, 6 figure
The spacetime structure of MOND with Tully-Fisher relation and Lorentz invariance violation
It is believed that the modification of Newtonian dynamics (MOND) is possible
alternate for dark matter hypothesis. Although Bekenstein's TeVeS supplies a
relativistic version of MOND, one may still wish a more concise covariant
formulism of MOND. In this paper, within covariant geometrical framwork, we
present another version of MOND. We show the spacetime structure of MOND with
properties of Tully-Fisher relation and Lorentz invariance violation.Comment: 6 pages. arXiv admin note: substantial text overlap with
arXiv:1111.1383 and arXiv:1108.344
A unified description for dipoles of the fine-structure constant and SnIa Hubble diagram in Finslerian universe
Design and Status of the Dipole Spectrometer Magnet for the ALICE Experiment
Proposal of abstract for MT16, Tallahesse, Florida, 26th September to 2nd October 1999.A large Dipole Magnet is required for the Muon Arm Spectrometer of the ALICE experiment at the LHC.The absence of strong requirements on the symmetry and homogeneity of the magnetic field has lead to a design dominated by economic and feasibility considerations.In March 1997 the decision was taken to build a resistive dipole magnet for the muon spectrometer of the ALICE experiment. Since then, design work has been pursued in JINR/Russia and at CERN. While a common concept has been adopted for the construction of the steel core, two different proposals have been made for the manufacturing technology of the excitation coils. In both cases, however, the conductor material will be Aluminium.The general concept of the dipole magnet is based on a window frame return yoke, fabricated from low carbon steel sheets. The flat vertical poles follow the defined acceptance angle of 9 degrees. The excitation coils are of saddle type. The coils are wound from large hollow Aluminium profiles. They are cooled by pressurized demineralised water. The coil ends are located to both sides of the magnet yoke and determine the overall length of the magnet. The main flux direction in the gap is horizontal and perpendicular to the LHC beam axis.Both coil concepts and the underlying manufacturing technology are compared and the present status of the development of the magnet is described
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