Quantum fluctuations in superconducting nanostructures

Research output: ThesisDissertationMonograph

Abstract

Modern nanofabrication technology enableTfabrication of very narrow quasi-1-dimensional superconducting nanowires demonstrating finite resistivity within the range of experimentally obtainable temperatures. The observations were reported in ∼10 nm nanowires of certain superconducting materials. The effect has been associated with quantum phase slip process - the particular manifestation of quantum fluctuations of the order p arameter. In titanium, the phenomenon can be observed already at dimensions ∼35 nm where the fabrication is well reproducible and the dimensions of samples can be characterized with high accuracy. We have performed systematic study of the size dependence of transport properties for superconducting ultra-narrow titanium nanowires utilizing method of gradual size reduction by low energetic ion beam milling. The method enables the study of the same nanowire with 1 nm effective diameter reduction between measurement cycles. The experiments demonstrated clear crossover to fluctuation dominated regime when the dimensions are reduced below a certain threshold. All available at our disposal microscopic analyses indicate no damage or contamination of the bulk of the nanowire due to the ion milling.
The next stage of the work was to demonstrate experimentally the quantum duality between the physics of Josephson junction and superconducting nanowire governed by quantum fluctuations. We showed that sufficiently narrow nanowires embedded in high-impedance environment demonstrate the insulating state - Coulomb blockade. The system can be considered as a single Cooper pair transistor without any dielectric barriers. Irradiation of the nanowire with external RF drive leads to formation of the Bloch steps on the IV characteristics - the phenomenon dual to the well-known Shapiro effect, currently used as quantum standard of electric voltage. We have performed experiments demonstrating the corresponding current singularities which confirm the hypothesis. The observation is of significant importance for both scientific and metrological communities.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Jyväskylä
Supervisors/Advisors
  • Arutyunov, Konstantin Yu., Supervisor, External person
Award date13 Jun 2014
Publisher
Print ISBNs978-951-39-5688-2
Electronic ISBNs978-951-39-5689-9
Publication statusPublished - 2014
MoE publication typeG4 Doctoral dissertation (monograph)

Fingerprint

nanowires
titanium
nanofabrication
disposal
Josephson junctions
crossovers
contamination
slip
transistors
transport properties
ion beams
impedance
damage
cycles
fabrication
electrical resistivity
physics
irradiation
thresholds
electric potential

Keywords

  • superconductor
  • fluctuation
  • phase slip
  • Bloch oscillation
  • QPS-transistor
  • 1-dimensional
  • titanium
  • ion milling

Cite this

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title = "Quantum fluctuations in superconducting nanostructures",
abstract = "Modern nanofabrication technology enableTfabrication of very narrow quasi-1-dimensional superconducting nanowires demonstrating finite resistivity within the range of experimentally obtainable temperatures. The observations were reported in ∼10 nm nanowires of certain superconducting materials. The effect has been associated with quantum phase slip process - the particular manifestation of quantum fluctuations of the order p arameter. In titanium, the phenomenon can be observed already at dimensions ∼35 nm where the fabrication is well reproducible and the dimensions of samples can be characterized with high accuracy. We have performed systematic study of the size dependence of transport properties for superconducting ultra-narrow titanium nanowires utilizing method of gradual size reduction by low energetic ion beam milling. The method enables the study of the same nanowire with 1 nm effective diameter reduction between measurement cycles. The experiments demonstrated clear crossover to fluctuation dominated regime when the dimensions are reduced below a certain threshold. All available at our disposal microscopic analyses indicate no damage or contamination of the bulk of the nanowire due to the ion milling.The next stage of the work was to demonstrate experimentally the quantum duality between the physics of Josephson junction and superconducting nanowire governed by quantum fluctuations. We showed that sufficiently narrow nanowires embedded in high-impedance environment demonstrate the insulating state - Coulomb blockade. The system can be considered as a single Cooper pair transistor without any dielectric barriers. Irradiation of the nanowire with external RF drive leads to formation of the Bloch steps on the IV characteristics - the phenomenon dual to the well-known Shapiro effect, currently used as quantum standard of electric voltage. We have performed experiments demonstrating the corresponding current singularities which confirm the hypothesis. The observation is of significant importance for both scientific and metrological communities.",
keywords = "superconductor, fluctuation, phase slip, Bloch oscillation, QPS-transistor, 1-dimensional, titanium, ion milling",
author = "Janne Lehtinen",
year = "2014",
language = "English",
isbn = "978-951-39-5688-2",
publisher = "University of Jyv{\"a}skyl{\"a}",
address = "Finland",
school = "University of Jyv{\"a}skyl{\"a}",

}

Lehtinen, J 2014, 'Quantum fluctuations in superconducting nanostructures', Doctor Degree, University of Jyväskylä.

Quantum fluctuations in superconducting nanostructures. / Lehtinen, Janne.

University of Jyväskylä, 2014. 100 p.

Research output: ThesisDissertationMonograph

TY - THES

T1 - Quantum fluctuations in superconducting nanostructures

AU - Lehtinen, Janne

PY - 2014

Y1 - 2014

N2 - Modern nanofabrication technology enableTfabrication of very narrow quasi-1-dimensional superconducting nanowires demonstrating finite resistivity within the range of experimentally obtainable temperatures. The observations were reported in ∼10 nm nanowires of certain superconducting materials. The effect has been associated with quantum phase slip process - the particular manifestation of quantum fluctuations of the order p arameter. In titanium, the phenomenon can be observed already at dimensions ∼35 nm where the fabrication is well reproducible and the dimensions of samples can be characterized with high accuracy. We have performed systematic study of the size dependence of transport properties for superconducting ultra-narrow titanium nanowires utilizing method of gradual size reduction by low energetic ion beam milling. The method enables the study of the same nanowire with 1 nm effective diameter reduction between measurement cycles. The experiments demonstrated clear crossover to fluctuation dominated regime when the dimensions are reduced below a certain threshold. All available at our disposal microscopic analyses indicate no damage or contamination of the bulk of the nanowire due to the ion milling.The next stage of the work was to demonstrate experimentally the quantum duality between the physics of Josephson junction and superconducting nanowire governed by quantum fluctuations. We showed that sufficiently narrow nanowires embedded in high-impedance environment demonstrate the insulating state - Coulomb blockade. The system can be considered as a single Cooper pair transistor without any dielectric barriers. Irradiation of the nanowire with external RF drive leads to formation of the Bloch steps on the IV characteristics - the phenomenon dual to the well-known Shapiro effect, currently used as quantum standard of electric voltage. We have performed experiments demonstrating the corresponding current singularities which confirm the hypothesis. The observation is of significant importance for both scientific and metrological communities.

AB - Modern nanofabrication technology enableTfabrication of very narrow quasi-1-dimensional superconducting nanowires demonstrating finite resistivity within the range of experimentally obtainable temperatures. The observations were reported in ∼10 nm nanowires of certain superconducting materials. The effect has been associated with quantum phase slip process - the particular manifestation of quantum fluctuations of the order p arameter. In titanium, the phenomenon can be observed already at dimensions ∼35 nm where the fabrication is well reproducible and the dimensions of samples can be characterized with high accuracy. We have performed systematic study of the size dependence of transport properties for superconducting ultra-narrow titanium nanowires utilizing method of gradual size reduction by low energetic ion beam milling. The method enables the study of the same nanowire with 1 nm effective diameter reduction between measurement cycles. The experiments demonstrated clear crossover to fluctuation dominated regime when the dimensions are reduced below a certain threshold. All available at our disposal microscopic analyses indicate no damage or contamination of the bulk of the nanowire due to the ion milling.The next stage of the work was to demonstrate experimentally the quantum duality between the physics of Josephson junction and superconducting nanowire governed by quantum fluctuations. We showed that sufficiently narrow nanowires embedded in high-impedance environment demonstrate the insulating state - Coulomb blockade. The system can be considered as a single Cooper pair transistor without any dielectric barriers. Irradiation of the nanowire with external RF drive leads to formation of the Bloch steps on the IV characteristics - the phenomenon dual to the well-known Shapiro effect, currently used as quantum standard of electric voltage. We have performed experiments demonstrating the corresponding current singularities which confirm the hypothesis. The observation is of significant importance for both scientific and metrological communities.

KW - superconductor

KW - fluctuation

KW - phase slip

KW - Bloch oscillation

KW - QPS-transistor

KW - 1-dimensional

KW - titanium

KW - ion milling

M3 - Dissertation

SN - 978-951-39-5688-2

PB - University of Jyväskylä

ER -

Lehtinen J. Quantum fluctuations in superconducting nanostructures. University of Jyväskylä, 2014. 100 p.