Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1901.02575 · Fortschritte der Physik

Quantum phase slips and voltage fluctuations in superconducting nanowires

Andrew G. Semenov, Andrei D. Zaikin

Published Feb 6, 2017• 8 citations
arXivHTMLPDF

Abstract

We argue that quantum phase slips (QPS) may generate non‐equilibrium voltage fluctuations in superconducting nanowires. In the low frequency limit we evaluate all cumulants of the voltage operator which obey Poisson statistics and show a power law dependence on the external bias. We specifically address quantum shot noise which power spectrum may depend non‐monotonously on temperature. In the long wire limit decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at . Our predictions can be directly tested in future experiments with superconducting nanowires.

DOI
10.1002/prop.201600043

Related papers

Quantum fluctuations of voltage in superconducting nanowires

Andrew G. Semenov, Andrei D. Zaikin

At low temperatures non-equilibrium voltage fluctuations can be generated in current-biased superconducting nanowires due to proliferation of quantum phase slips (QPS) or, equivalently, due to quantum tunneling of magnetic flux quanta across the wire. In this paper we review and further extend recent theoretical results related to this phenomenon. Employing the phase-charge duality arguments combined with Keldysh path integral technique we analyze such fluctuations within the two-point and four-point measurement schemes demonstrating that voltage noise detected in such nanowires in general depends on the particular measurement setup. In the low frequency limit we evaluate all cumulants of the voltage operator which turn out to obey Poisson statistics and exhibit a power law dependence on the external bias. We also specifically address a non-trivial frequency dependence of quantum shot noise power spectrum SΩ for both longer and shorter superconducting nanowires. In particular, we demonstrate that SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T → 0. Furthermore, we predict that SΩ may depend non-monotonously on temperature due to quantum coherent nature of QPS noise. The results of our theoretical analysis can be directly tested in future experiments with superconducting nanowires.

Low Temperature Physics•Jul 1, 2017•2 citations

Evolution of phase slips with wire width and observation of critical-voltage feature without high-impedance environment in NbN nanowires

Xiaoni Wang, Zulei Xu, Xiaoyu Liu +10 more

Abstract Quantum phase slip (QPS) is an important effect that occurs in one-dimensional (1D) or quasi-1D superconducting (SC) materials. Due to the extremely high requirements on the uniformity and quality of SC nanowires, it is currently very challenging to obtain repeatable and controllable QPS devices. Here, we report a systematic study of the QPS effect in NbN SC nanowires. High-quality NbN nanowires with different widths are fabricated by combining the processes of photo-lithography, electron beam lithography, and inductively coupled plasma etching. It is found that the electrical transport of the nanowires showed a systematic variation with the wire width, and a clear evolution from single to multiple QPS events with the decrease in wire width is uncovered at low temperatures. Based on these experimental results, the phase diagram reflecting the evolution of the physical states of the nanowires with wire width and temperature is obtained. In addition, we observed the features of the critical voltage, which is a characteristic of the occurrence of coherent QPS (cQPS), in samples with a width of 36 nm in the multiple QPS region. It is worth noting that this cQPS behavior was detected in a non-high-impedance environment.

Superconductor Science and Technology•Jan 30, 2024•3 citations

Probing quantum phase slips in superconducting nanowires modified using high bias voltage pulses

Thomas Aref

Quantum phase slips (QPS) or the macroscopic quantum tunneling (MQT) of a nanowire’s order parameter through an activation energy barrier have remained the subject of intense debate for many years. They are expected to occur at low enough temperature where thermally activated phase slips (TAPS) have been frozen out in analogy with Josephson junctions where the macroscopic tunneling of phase at low temperatures has been conclusively experimentally demonstrated. We address this question by following a similar experimental strategy to that employed for establishing MQT in JJs. By measuring switching current distributions, we can probe the phase slip rate and determine if it corresponds to thermal activation or quantum tunneling. Having established that the behavior we see is consistent with being in the quantum regime, we can alter properties of the nanowires and see if the response is consistent with the expectations of the quantum model. To do this we employ an in-situ modification technique using high bias voltage pulses. Using these pulses, we can change resistance, critical temperature, critical current and morphology of the nanowire. We can also change the shunting capacitance of the nanowire by altering the photolithography step used to create the nanowires electrodes. The resulting response of the nanowires agrees well with being in the quantum tunneling dominated regime. An interesting side benefit of the pulsing technique is that we can exactly set the nanowires switching current to a desired value. This may be instrumental in the development of superconducting nanowire qubits.

•Jan 1, 2010•0 citations

Stochastic and deterministic phase slippage in quasi-one-dimensional superconducting nanowires exposed to microwaves

Myung‐Ho Bae, R. C. Dinsmore, Mitrabhanu Sahu +1 more

We study current–voltage ( V – I ) characteristics of short superconducting nanowires of length ∼100 nm exposed to microwave (MW) radiation of frequencies between 2 and 15 GHz. The radiation causes a decrease of the average switching current of the wire. This suppression of the switching current is modeled assuming that there is one-to-one correspondence between Little's phase slips, which are microscopic stochastic events induced by thermal and quantum fluctuations, and the experimentally observed switching events. We also find that at some critical power P * of the radiation a dissipative dynamic superconducting state occurs as an extra step on the V – I curve. It is identified as a phase slip center (PSC), which is essentially a deterministic and periodic in-time phase rotation. With the dependence of the switching currents and the standard deviations observed at the transitions: (i) from the supercurrent state to the normal state and (ii) from the supercurrent state to the PSC regime, we conclude that both of the two types of switching events are triggered by the same microscopic event, namely a single-phase slip. We show that the Skocpol–Beasley–Tinkham model is not applicable to our MW-driven PSCs, probably due to the tendency of the PSC to synchronize with the MW. Through the analysis of the switching current distributions at a sufficiently low temperature, we also present evidence that quantum phase slips play a role in switching events even under MWs.

New Journal of Physics•Apr 17, 2012•10 citations

Observation of individual macroscopic quantum tunneling events in superconducting nanowires

Meenakshi Singh, Moses H. W. Chan

In quasi-one-dimensional nanowires, superconductivity is destroyed by phase slip events. Phase slips can be caused by thermal activation over a free energy barrier (TAPS) or quantum tunneling through the barrier (QPS). Quantum phase slip is an example of macroscopic quantum tunneling. Here, we report the observation of QPS experimentally separated from interference of TAPS in aluminum nanowires. This separation between the low-temperature QPS and the high-temperature TAPS regions is made possible by a phase slip free superconducting region stabilized by the dissipative environment viz. the normal electrodes. Individual QPSs are detected by means of a single-shot voltage measurement protocol, in which they appear as stochastic switching events from the superconducting to the normal state.

Physical Review B•Aug 26, 2013•14 citations

Coherent Quantum Phase-Slips in Superconducting Nanowires in DC Transport

JC Fenton, Jonathan Burnett

The phenomenon of coherent quantum phase-slips (CQPS) in superconducting nanowires was some time ago proposed to be the exact dual of the Josephson effect, a proposal accompanied by predictions of a new quantum current standard dual to the Josephson voltage standard. Unambiguous experimental observation of CQPS in nanowire structures has only recently been achieved through microwave spectroscopy which showed an avoided crossing between flux states for a superconducting ring interrupted by a superconducting nanowire. This observation raises expectations that the CQPS quantum current standard and a slew of CQPS devices dual to devices containing Josephson junction might be realised, including a tunable capacitance, a sensitive charge detector and small-signal detector. To date, experimental evidence for CQPS in a dc transport geometry has not been considered conclusive, and the impact of decoherence in CQPS devices still remains to be evaluated. We present experimental work which has enabled us to crystallise pertinent issues which have prevented the realisation of CQPS in dc transport experiments to date.

•Aug 7, 2014•0 citations
We argue that quantum phase slips (QPS) may generate non‐equilibrium voltage fluctuations in superconducting nanowires. In the low frequency limit we evaluate all cumulants of the voltage operator which obey Poisson statistics and show a power law dependence on the external bias. We specifically address quantum shot noise which power spectrum may depend non‐monotonously on temperature. In the long wire limit decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at . Our predictions can be directly tested in future experiments with superconducting nanowires.
At low temperatures non-equilibrium voltage fluctuations can be generated in current-biased superconducting nanowires due to proliferation of quantum phase slips (QPS) or, equivalently, due to quantum tunneling of magnetic flux quanta across the wire. In this paper we review and further extend recent theoretical results related to this phenomenon. Employing the phase-charge duality arguments combined with Keldysh path integral technique we analyze such fluctuations within the two-point and four-point measurement schemes demonstrating that voltage noise detected in such nanowires in general depends on the particular measurement setup. In the low frequency limit we evaluate all cumulants of the voltage operator which turn out to obey Poisson statistics and exhibit a power law dependence on the external bias. We also specifically address a non-trivial frequency dependence of quantum shot noise power spectrum SΩ for both longer and shorter superconducting nanowires. In particular, we demonstrate that SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T → 0. Furthermore, we predict that SΩ may depend non-monotonously on temperature due to quantum coherent nature of QPS noise. The results of our theoretical analysis can be directly tested in future experiments with superconducting nanowires.
Abstract Quantum phase slip (QPS) is an important effect that occurs in one-dimensional (1D) or quasi-1D superconducting (SC) materials. Due to the extremely high requirements on the uniformity and quality of SC nanowires, it is currently very challenging to obtain repeatable and controllable QPS devices. Here, we report a systematic study of the QPS effect in NbN SC nanowires. High-quality NbN nanowires with different widths are fabricated by combining the processes of photo-lithography, electron beam lithography, and inductively coupled plasma etching. It is found that the electrical transport of the nanowires showed a systematic variation with the wire width, and a clear evolution from single to multiple QPS events with the decrease in wire width is uncovered at low temperatures. Based on these experimental results, the phase diagram reflecting the evolution of the physical states of the nanowires with wire width and temperature is obtained. In addition, we observed the features of the critical voltage, which is a characteristic of the occurrence of coherent QPS (cQPS), in samples with a width of 36 nm in the multiple QPS region. It is worth noting that this cQPS behavior was detected in a non-high-impedance environment.
Quantum phase slips (QPS) or the macroscopic quantum tunneling (MQT) of a nanowire’s order parameter through an activation energy barrier have remained the subject of intense debate for many years. They are expected to occur at low enough temperature where thermally activated phase slips (TAPS) have been frozen out in analogy with Josephson junctions where the macroscopic tunneling of phase at low temperatures has been conclusively experimentally demonstrated. We address this question by following a similar experimental strategy to that employed for establishing MQT in JJs. By measuring switching current distributions, we can probe the phase slip rate and determine if it corresponds to thermal activation or quantum tunneling. Having established that the behavior we see is consistent with being in the quantum regime, we can alter properties of the nanowires and see if the response is consistent with the expectations of the quantum model. To do this we employ an in-situ modification technique using high bias voltage pulses. Using these pulses, we can change resistance, critical temperature, critical current and morphology of the nanowire. We can also change the shunting capacitance of the nanowire by altering the photolithography step used to create the nanowires electrodes. The resulting response of the nanowires agrees well with being in the quantum tunneling dominated regime. An interesting side benefit of the pulsing technique is that we can exactly set the nanowires switching current to a desired value. This may be instrumental in the development of superconducting nanowire qubits.
We study current–voltage ( V – I ) characteristics of short superconducting nanowires of length ∼100 nm exposed to microwave (MW) radiation of frequencies between 2 and 15 GHz. The radiation causes a decrease of the average switching current of the wire. This suppression of the switching current is modeled assuming that there is one-to-one correspondence between Little's phase slips, which are microscopic stochastic events induced by thermal and quantum fluctuations, and the experimentally observed switching events. We also find that at some critical power P * of the radiation a dissipative dynamic superconducting state occurs as an extra step on the V – I curve. It is identified as a phase slip center (PSC), which is essentially a deterministic and periodic in-time phase rotation. With the dependence of the switching currents and the standard deviations observed at the transitions: (i) from the supercurrent state to the normal state and (ii) from the supercurrent state to the PSC regime, we conclude that both of the two types of switching events are triggered by the same microscopic event, namely a single-phase slip. We show that the Skocpol–Beasley–Tinkham model is not applicable to our MW-driven PSCs, probably due to the tendency of the PSC to synchronize with the MW. Through the analysis of the switching current distributions at a sufficiently low temperature, we also present evidence that quantum phase slips play a role in switching events even under MWs.
In quasi-one-dimensional nanowires, superconductivity is destroyed by phase slip events. Phase slips can be caused by thermal activation over a free energy barrier (TAPS) or quantum tunneling through the barrier (QPS). Quantum phase slip is an example of macroscopic quantum tunneling. Here, we report the observation of QPS experimentally separated from interference of TAPS in aluminum nanowires. This separation between the low-temperature QPS and the high-temperature TAPS regions is made possible by a phase slip free superconducting region stabilized by the dissipative environment viz. the normal electrodes. Individual QPSs are detected by means of a single-shot voltage measurement protocol, in which they appear as stochastic switching events from the superconducting to the normal state.
The phenomenon of coherent quantum phase-slips (CQPS) in superconducting nanowires was some time ago proposed to be the exact dual of the Josephson effect, a proposal accompanied by predictions of a new quantum current standard dual to the Josephson voltage standard. Unambiguous experimental observation of CQPS in nanowire structures has only recently been achieved through microwave spectroscopy which showed an avoided crossing between flux states for a superconducting ring interrupted by a superconducting nanowire. This observation raises expectations that the CQPS quantum current standard and a slew of CQPS devices dual to devices containing Josephson junction might be realised, including a tunable capacitance, a sensitive charge detector and small-signal detector. To date, experimental evidence for CQPS in a dc transport geometry has not been considered conclusive, and the impact of decoherence in CQPS devices still remains to be evaluated. We present experimental work which has enabled us to crystallise pertinent issues which have prevented the realisation of CQPS in dc transport experiments to date.