| 1. |
- Bauch, Thilo, 1972, et al.
(författare)
-
Correlated quantization of supercurrent and conductance in a superconducting quantum point contact
- 2005
-
Ingår i: Physical Review B. ; 71:17, s. 174502-
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured the supercurrent and conductance of a superconducting quantum point contact in a superconductor two-dimensional electron gas-superconductor Josephson junction. We observe that the supercurrent and conductance change stepwise in a correlated manner as a function of the gate voltage. This was achieved by simultaneous measurement of the supercurrent and conductance at high bias from the same current voltage characteristic.
|
|
| 2. |
|
|
| 3. |
- Bauch, Thilo, 1972, et al.
(författare)
-
Dynamics of d-wave YBa2Cu3O7-x
- 2007
-
Ingår i: Superconductor Science and Technology. - 0953-2048 .- 1361-6668. ; 20:2, s. S98-S104
-
Konferensbidrag (refereegranskat)abstract
- The predominant d-wave pairing symmetry in high temperature superconductors leads to an unconventional current phase relation in Josephson junctions. This circumstance may induce new effects in the dynamics of dc SQUIDs. In this contribution we report on the measurements of the dependence of the SQUID Josephson current on the external magnetic field taken at very low temperatures, down to 20 mK. Different grain boundaries have been fabricated by using the biepitaxial and the bicrystal technique. Some of the effects which are induced by a nonsinusoidal current phase relation can be clearly identified in the dynamics of the SQUIDs. The experimental data are also compared with theoretical simulations taking into account the inductance of the loop. The data show that, in specific conditions, a non-negligible inductance of the loop can induce effects similar to an unconventional current phase relation, with a pronounced second harmonic sin(2) term. This fact has to be taken into account when designing d-wave SQUIDs for quantum circuitry.
|
|
| 4. |
- Bauch, Thilo, 1972, et al.
(författare)
-
High critical temperature superconductor Josephson junctions for quantum circuit applications
- 2009
-
Ingår i: Physica Scripta. ; T137, s. 014006-
-
Konferensbidrag (refereegranskat)abstract
- Recent findings of macroscopic quantum properties in high critical temperature superconductor (HTS) Josephson junctions (JJs) point toward the need to revise the role of zero energy quasi-particles in this novel superconductor. We will discuss the possibility of designing superconducting artificial atoms in a transmon configuration to study the low energy excitation spectra of HTS. We have engineered high quality grain boundary JJs on low dielectric constant substrates. By fabricating submicron junctions, we extract values of capacitance and Josephson critical current densities that satisfy the main transmon design requirements. Moreover, the measured critical current noise power extrapolated at 1 Hz gives a dephasing time of 25 ns, which indicates that the observation of macroscopic quantum coherent effects in HTS JJ is a feasible task.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Bauch, Thilo, 1972, et al.
(författare)
-
YBCOSQUIDs with unconventional current phase relation
- 2007
-
Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 463-465:1 October 2007, s. 979-984
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the dynamics of YBa2Cu3O7-delta,5 (YBCO) dc sperconducting quantum interference devices (SQUIDs) characterized by an unconventional Josephson current phase relation (CPR). We have focused on SQUID configurations with Josephson junctions where the lobe of the order parameter in one electrode is facing a node in the other electrode. This order parameter arrangement should enhance the appearance of a sin(2(p) term in the CPR. The response of the critical current of the dc SQUID, under the effect of an external magnetic field, has been measured in temperature, down to 20 mK. Our experimental data have been compared with numerical simulations of the SQUIDs dynamics by considering a CPR of a single junction of the form I(phi) = I-I sin(phi) - I-II sin(2 phi) where I-I, and I-II are, respectively, the first and second harmonic component. In our devices the values of the sin(2 phi) term are such that the fundamental state of the SQUID is naturally double degenerate. This is of great relevance for applications of d-wave SQUIDs in quantum information processing. (C) 2007 Elsevier B.V. All rights reserved.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Greibe, Tine, 1974, et al.
(författare)
-
Improvement of chip design to reduce resonances in subgap regime of Josephson junctions
- 2009
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 150, s. 052063-
-
Konferensbidrag (refereegranskat)abstract
- Excess current peaks in the IV curves of SIS Josephson junctions have been observed by some groups [1–3]. These peaks have the shape of a resonance as a function of voltage. The resonances appear in the subgap regime of the junctions and the subgap current (leakage current) is concealed. The positions of the resonances do not change as a magnetic field is applied to the junctions, but their amplitude decreases when the supercurrent is suppressed. We have measured the subgap current of Al/AlOx/Al junctions and we show that these resonances are due to resonant modes in the chip design which are excited by the ac-Josephson effect. We present a chip design that decreases the amplitude of the resonances to a such degree that the subgap current is quantifiable.
|
|
