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:0710.2760 · Physical Review B

Quantitative study of quasiparticle traps using the single-Cooper-pair transistor

Nadia Court, Andrew J. Ferguson, Roman M. Lutchyn, Robert G. Clark

Published Mar 6, 2008• 55 citations
arXivHTMLPDF

Abstract

We use radio-frequency reflectometry to measure quasiparticle tunneling rates in the single-Cooper-pair transistor. Devices with and without quasiparticle traps in proximity to the island are studied. A ${10}^{2}$- to ${10}^{3}$-fold reduction in the quasiparticle tunneling rate onto the island is observed in the case of quasiparticle traps. In the quasiparticle trap samples we also measure a commensurate decrease in quasiparticle tunneling rate off the island.

DOI
10.1103/physrevb.77.100501

Related papers

Time-domain measurements of quasiparticle tunneling rates in a single-Cooper-pair transistor

Ofer Naaman, José Aumentado

We have measured, in real time, individual quasiparticle tunneling in a single-Cooper-pair transistor, using rf reflectometry on the supercurrent branch. We have extracted the even-to-odd and odd-to-even transition rates directly by analyzing the distributions of dwell times in the even and odd states of the transistor. We discuss both the measurement and analysis techniques and report on the temperature and gate dependence of the quasiparticle tunneling rates.

arXiv:cond-mat/0602004•Physical Review B•May 19, 2006•59 citations

Quasiparticle cooling of a single Cooper pair transistor

Andrew J. Ferguson

A superconducting tunnel junction is used to directly extract quasiparticles from one of the leads of a single Cooper pair transistor. The consequent reduction in quasiparticle density causes a lower rate of quasiparticle tunneling onto the device. This rate is directly measured by radio-frequency reflectometry. Local cooling may be of direct benefit in reducing the effect of quasiparticles on coherent superconducting nanostructures.

arXiv:0805.3445•Applied Physics Letters•Aug 4, 2008•6 citations

Microsecond Resolution of Quasiparticle Tunneling in the Single-Cooper-Pair Transistor

Andrew J. Ferguson, Nadia Court, Fay E. Hudson +1 more

We present radio-frequency measurements on a single-Cooper-pair-transistor in which individual quasiparticle poisoning events were observed with microsecond temporal resolution. Thermal activation of the quasiparticle dynamics is investigated, and consequently, we are able to determine energetics of the poisoning and unpoisoning processes. In particular, we are able to assign an effective quasiparticle temperature to parametrize the poisoning rate.

arXiv:cond-mat/0604403•Physical Review Letters•Sep 7, 2006•60 citations

Detecting parity effect in a superconducting device in the presence of parity switches

E. T. Mannila, V. F. Maisi, Hung Q. Nguyen +2 more

We present a superconducting device showing a clear parity effect in the number of electrons, even when there is, on average, a single nonequilibrium quasiparticle present and the parity of the island switches due to quasiparticles tunneling in and out of the device at rates on the order of 100 Hz. We detect the switching by monitoring in real time the charge state of a superconducting island connected to normal leads by tunnel junctions. The quasiparticles are created by Cooper pairs breaking on the island at a rate of a few kilohertz. We demonstrate that the pair breaking is caused by the backaction of the single-electron transistor used as a charge detector. With sufficiently low probing currents, our superconducting island is free of quasiparticles 97% of the time.

arXiv:1807.01733•Physical review. B./Physical review. B•Jul 8, 2019•15 citations

Radio-frequency-induced transport of Cooper pairs in superconducting single electron transistors in a dissipative environment

S. V. Lotkhov, Sergey A. Bogoslovsky, Alexander B Zorin +1 more

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 samples with relatively large charging energy Ec>EJ, where EJ is the Josephson coupling energy, two transport mechanisms were found to be dominant, 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 conducting 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 conducting state of our transistors had been found to be subject 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.

arXiv:cond-mat/0312152•Journal of Applied Physics•May 17, 2004•7 citations

The single-electron transistor as an ultrasensitive microwave detector

J. M. Hergenrother, Jia Grace Lu, M. Tinkham

We have measured single-electron tunneling transistors with superconducting islands and conclude that they may be used as ultrasensitive detectors of microwave radiation for frequencies /spl ges/80 GHz. These devices contain a small superconducting Al island that is weakly coupled to a bias circuit through two small-capacitance tunnel junctions and a capacitive gate. At low bias voltages and temperatures, a single quasiparticle may only be introduced to the island through photon-assisted tunneling. Once this occurs, the quasiparticle is trapped on the island for /spl sim/1 /spl mu/s because it takes a relatively long time for this specific quasiparticle to tunnel off. While it is trapped, charge is transported through the system two electrons at a time. Since the photon-assisted transition merely switches the detector current on, this device is not limited to one electron tunneled through the system per absorbed photon. Measurements indicate that at least 100 electrons can tunnel for every absorbed photon, which corresponds to a noise-equivalent power of 3/spl times/10/sup -20/ W//spl radic/Hz at 80 GHz if the current is measured with a commercial current amplifier.>

IEEE Transactions on Applied Superconductivity•Jun 1, 1995•7 citations
We use radio-frequency reflectometry to measure quasiparticle tunneling rates in the single-Cooper-pair transistor. Devices with and without quasiparticle traps in proximity to the island are studied. A 102{10}^{2}102- to 103{10}^{3}103-fold reduction in the quasiparticle tunneling rate onto the island is observed in the case of quasiparticle traps. In the quasiparticle trap samples we also measure a commensurate decrease in quasiparticle tunneling rate off the island.
We present a superconducting device showing a clear parity effect in the number of electrons, even when there is, on average, a single nonequilibrium quasiparticle present and the parity of the island switches due to quasiparticles tunneling in and out of the device at rates on the order of 100 Hz. We detect the switching by monitoring in real time the charge state of a superconducting island connected to normal leads by tunnel junctions. The quasiparticles are created by Cooper pairs breaking on the island at a rate of a few kilohertz. We demonstrate that the pair breaking is caused by the backaction of the single-electron transistor used as a charge detector. With sufficiently low probing currents, our superconducting island is free of quasiparticles 97% of the time.
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 samples with relatively large charging energy Ec>EJ, where EJ is the Josephson coupling energy, two transport mechanisms were found to be dominant, 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 conducting 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 conducting state of our transistors had been found to be subject 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.
We have measured single-electron tunneling transistors with superconducting islands and conclude that they may be used as ultrasensitive detectors of microwave radiation for frequencies /spl ges/80 GHz. These devices contain a small superconducting Al island that is weakly coupled to a bias circuit through two small-capacitance tunnel junctions and a capacitive gate. At low bias voltages and temperatures, a single quasiparticle may only be introduced to the island through photon-assisted tunneling. Once this occurs, the quasiparticle is trapped on the island for /spl sim/1 /spl mu/s because it takes a relatively long time for this specific quasiparticle to tunnel off. While it is trapped, charge is transported through the system two electrons at a time. Since the photon-assisted transition merely switches the detector current on, this device is not limited to one electron tunneled through the system per absorbed photon. Measurements indicate that at least 100 electrons can tunnel for every absorbed photon, which corresponds to a noise-equivalent power of 3/spl times/10/sup -20/ W//spl radic/Hz at 80 GHz if the current is measured with a commercial current amplifier.>