4 research outputs found
Reemergence of missing Shapiro steps in the presence of in-plane magnetic field
In the presence of a 4-periodic contribution to the current phase
relation, for example in topological Josephson junctions, odd Shapiro steps are
expected to be missing. While missing odd Shapiro steps have been observed in
several material systems and interpreted in the context of topological
superconductivity, they have also been observed in topologically trivial
junctions. Here, we study the evolution of such trivial missing odd Shapiro
steps in Al-InAs junctions in the presence of an in-plane magnetic field
. We find that the odd steps reappear at a crossover
value, exhibiting an in-plane field angle anisotropy that depends on spin-orbit
coupling effects. We interpret this behavior by theoretically analyzing the
Andreev bound state spectrum and the transitions induced by the non-adiabatic
dynamics of the junction. Our results highlight the complex phenomenology of
missing Shapiro steps and the underlying current phase relations in planar
Josephson junctions designed to realize Majorana states
Superconducting resonators with voltage-controlled frequency and nonlinearity
Voltage-tunable superconductor-semiconductor devices offer a unique platform
to realize dynamic tunability in superconducting quantum circuits. By
galvanically connecting a gated InAs-Al Josephson junction to a coplanar
waveguide resonator, we demonstrate the use of a wide-range gate-tunable
superconducting element. We show that the resonant frequency is controlled via
a gate-tunable Josephson inductance and that the non-linearity of the
voltage-controlled InAs-Al junction is non-dissipative as is the case with
conventional Al-AlO junctions. As the gate voltage is decreased, the
inductive participation of the junction increases up to , resulting in
the resonant frequency being tuned by over 2 GHz. Utilizing the wide tunability
of the device, we demonstrate that two resonant modes can be adjusted such that
they strongly hybridize, exhibiting an avoided level crossing with a coupling
strength of 51 MHz. Implementing such voltage-tunable resonators is the first
step toward realizing wafer-scale continuous voltage control in superconducting
circuits for qubit-qubit coupling, quantum-limited amplifiers, and quantum
memory platforms
Quasiparticle dynamics in epitaxial Al-InAs planar Josephson junctions
Quasiparticle (QP) effects play a significant role in the coherence and
fidelity of superconducting quantum circuits. The Andreev bound states of high
transparency Josephson junctions can act as low-energy traps for QPs, providing
a mechanism for studying the dynamics and properties of both the QPs and the
junction. We study the trapping and clearing of QPs from the Andreev bound
states of epitaxial Al-InAs Josephson junctions incorporated in a
superconducting quantum interference device (SQUID) galvanically shorting a
superconducting resonator to ground. We use a neighboring voltage-biased
Josephson junction to inject QPs into the circuit. Upon the injection of QPs,
we show that we can trap and clear QPs when the SQUID is flux-biased. We
examine effects of the microwave loss associated with bulk QP transport in the
resonator, QP-related dissipation in the junction, and QP poisoning events. By
monitoring the QP trapping and clearing in time, we study the dynamics of these
processes and find a time-scale of few microseconds that is consistent with
electron-phonon relaxation in our system and correlated QP trapping and
clearing mechanisms. Our results highlight the QP trapping and clearing
dynamics as well as the associated time-scales in high transparency Josephson
junctions based fabricated on Al-InAs heterostructures
Quasiparticle Dynamics in Epitaxial Al-InAs Planar Josephson Junctions
Quasiparticle (QP) effects play a significant role in the coherence and fidelity of superconducting quantum circuits. The Andreev bound states of high-transparency Josephson junctions can act as low-energy traps for QPs, providing a mechanism for studying the dynamics and properties of both the QPs and the junction. Using locally injected and thermal QPs, we study QP loss and QP poisoning in epitaxial Al-InAs Josephson junctions incorporated in a superconducting quantum interference device (SQUID) galvanically shorting a superconducting resonator to ground. We observe changes in the resonance line shape and frequency shifts consistent with QP trapping into and clearing out of the ABSs of the junctions when the junctions are phase biased. By monitoring the QP trapping and clearing mechanisms in time, we find a time scale of O(1μs) for these QP dynamics, consistent with the presence of phonon-mediated QP-QP interactions. Our measurements suggest that electron-phonon interactions play a significant role in the relaxation mechanisms of our system, while electron-photon interactions and electron-phonon interactions govern the clearing mechanisms. Our results highlight the QP-induced dissipation and complex QP dynamics in superconducting quantum circuits fabricated on superconductor-semiconductor heterostructures