arXiv subjects

C. J. M. Verwijs

Publications and source records attributed to C. J. M. Verwijs.

4 recordsLinked to original sources

arXiv2012

Optimizing the Majorana character of SQUIDs with topologically non-trivial barriers

We have modeled SQUIDs with topologically non-trivial superconducting junctions and performed an optimization study on the Majorana fermion detection. We find that the SQUID parameters beta_L, and beta_C can be used to increase the ratio of Majorana tunneling to standard Cooper pair tunneling by more than two orders of magnitude. Most importantly, we show that dc SQUIDs including topologically trivial components can still host strong signatures of the Majorana fermion. This paves the way towards the experimental verification of the theoretically predicted Majorana fermion.

cond-mat.supr-con↗

arXiv2009

Macroscopic quantum tunneling and quasiparticle-tunneling blockade effect in s-wave/d-wave hybrid junctions

We have theoretically investigated macroscopic quantum tunneling (MQT) and the influence of nodal quasiparticles and zero energy bound states (ZES) on MQT in s-wave/ d-wave hybrid Josephson junctions. In contrast to d-wave/d-wave junctions, the low-energy quasiparticle dissipation resulting from nodal quasiparticles and ZES is suppressed due to a quasiparticle-tunneling blockade effect in an isotropic s-wave superconductor. Therefore, the inherent dissipation in these junctions is found to be very weak. We have also investigated MQT in a realistic s-wave/d-wave (Nb/Au/YBCO) junction in which Ohmic dissipation in a shunt resistance is stronger than the inherent dissipation and find that MQT is observable within the current experimental technology. This result suggests high potential of s-wave/d-wave hybrid junctions for applications in quantum information devices.

cond-mat.supr-con↗

arXiv2006

Experiments using high-Tc/low-Tc Josephson contacts

Remarkably rich physics is involved in the behavior of hybrid Josephson junctions, connecting high-Tc and low-Tc superconductors. This relates in particular to the different order parameter symmetries underlying the formation of the superconducting states in these materials. Experiments on high-Tc/low-Tc contacts have also played a crucial role in settling the decade-long d-wave versus s-wave debate in cuprate superconductors. Recently, such hybrid junctions have enabled more detailed pairing symmetry tests. Furthermore, with these junctions, complex arrays of pi-rings have been realized, enabling studies on spontaneously generated fractional flux quanta and their mutual interactions. Steps toward novel superconducting electronic devices are taken, utilizing the phase-shifts inherent to the d-wave superconducting order parameter. This paper is intended to reflect the current status of experiments using high-Tc and low-Tc Josephson contacts.

cond-mat.supr-con↗

arXiv2004

Nondestructive readout for a superconducting flux qubit

We present a new readout method for a superconducting flux qubit, based on the measurement of the Josephson inductance of a superconducting quantum interference device that is inductively coupled to the qubit. The intrinsic flux detection efficiency and back-action are suitable for a fast and nondestructive determination of the quantum state of the qubit, as needed for readout of multiple qubits in a quantum computer. We performed spectroscopy of a flux qubit and we measured relaxation times of the order of 80 $μs$.

cond-mat.supr-con↗