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Nonlinear dynamics of Josephson Junction Chains and Superconducting Resonators
KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.ORCID iD: 0000-0003-0493-7792
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents the results of the experimental studies on two kindof Superconducting circuits: one-dimensional Josephson junction chains andsuperconducting coplanar waveguide (CPW) resonators. One-dimensionalJosephson junction chains are constructed by connecting many Superconducting quantum interference devices (SQUIDs) in series. We have studied DC transport properties of the SQUID chains and model their nonlineardynamics with Thermally Activated Phase-Slips (TAPS). Experimental andsimulated results showed qualitative agreement revealing the existence of auniform phase-slipping and phase-sticking process which results in a voltage-independent current on the dissipative branch of the current-voltage char-acteristics (IVC). By modulating the effective Josephson coupling energy ofthe SQUIDs (EJ ) with an external magnetic field, we found that the ratio EJ /EC is a decisive factor in determining the qualitative shape of theIVC. A quantum phase transition between incoherent Quantum Phase Slip, QPS (supercurrent branch with a finite slope) to coherent QPS (IVC withwell-developed Coulomb blockade) via an intermediate state (supercurrentbranch with a remnant of Coulomb blockade) is observed as the EJ /EC ratio is tuned. This transition from incoherent QPS to the intermediate-statehappens around R0 ∼ RQ (RQ = h/4e^2 = 6.45kΩ). We also fabricated structured chains where a SQUID at the middle of the chain (central SQUID) has different junction size and loop area compared to other SQUIDs in the chain. Results showed that with these structured chains it is possible to localize andtune the amplitude of both TAPS and QPS at the central SQUID.

The second part of the thesis describes the fabrication process and themeasurement results of superconducting CPW resonators. Resonators withdifferent design parameters were fabricated and measured. The transmissionspectra showed quality factors up to, Q ∼ 5 × 10^5 . We have observed bendingof the resonance curves to the lower frequencies due to existence of a nonlinear kinetic inductance. The origin of the nonlinear kinetic inductance isthe nonlinear relation between supercurrent density, Js, and superfluid veloc-ity, vs , of the charge carriers on the center line of the resonators. A simplemodel based on the Ginzburg-Landau theory is used in order to explain ob-served nonlinear kinetic inductance and estimates using this model showedgood agreement with the experimental results.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , vi, 119 p.
Series
Trita-FYS, ISSN 0280-316X ; 13:52
Keyword [en]
Superconductivity, Josephson Junction, SQUID, Superconducting Resonators
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kth:diva-132238ISBN: 978-91-7501-869-0 (print)OAI: oai:DiVA.org:kth-132238DiVA: diva2:659243
Public defence
2013-11-28, FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Projects
SCOPE
Funder
EU, FP7, Seventh Framework Programme
Note

QC 20131030

Available from: 2013-11-04 Created: 2013-10-24 Last updated: 2013-11-04Bibliographically approved
List of papers
1. Phase sticking in one-dimensional Josephson junction chains
Open this publication in new window or tab >>Phase sticking in one-dimensional Josephson junction chains
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2013 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, no 10, 104501- p.Article in journal (Refereed) Published
Abstract [en]

We studied current-voltage characteristics of long one-dimensional Josephson junction chains with Josephson energy much larger than charging energy, E-J >> E-C. In this regime, typical I-V curves of the samples consist of a supercurrent-like branch at low-bias voltages followed by a voltage-independent chain current branch, I-chain at high bias. Our experiments showed that I-chain is not only voltage-independent but it is also practically temperature-independent up to T = 0.7T(C). We have successfully model the transport properties in these chains using a capacitively shunted junction model with nonlinear damping.

Keyword
Superconducting Circuits, Coulomb-Blockade, Tunnel-Junctions, Arrays, Transition, Slips
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-129444 (URN)10.1103/PhysRevB.88.104501 (DOI)000323890700005 ()2-s2.0-84884886402 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20131002

Available from: 2013-10-02 Created: 2013-09-30 Last updated: 2017-12-06Bibliographically approved
2. Localizing quantum phase slips in one-dimensional Josephson junction chains
Open this publication in new window or tab >>Localizing quantum phase slips in one-dimensional Josephson junction chains
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2013 (English)In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 15, 095014- p.Article in journal (Refereed) Published
Abstract [en]

We studied quantum phase-slip (QPS) phenomena in long one-dimensional Josephson junction series arrays with tunable Josephson coupling. These chains were fabricated with as many as 2888 junctions, where one sample had a separately tunable link in the middle of the chain. Measurements were made of the zero-bias resistance, R-0, as well as current-voltage characteristics (IVC). The finite R-0 is explained by QPS and shows an exponential dependence on root E-J/E-C with a distinct change in the exponent at R-0 = R-Q = h/4e(2). When R-0 > R-Q, the IVC clearly shows a remnant of the Coulomb blockade, which evolves to a zero-current state with a sharp critical voltage as E-J is tuned to a smaller value. The zero-current state below the critical voltage is due to coherent QPSs and we show that these are enhanced when the central link is weaker than all other links. Above the critical voltage, a negative, differential resistance is observed, which nearly restores the zero-current state.

Keyword
Small Tunnel-Junctions, Charge Solitons, Arrays, Superconductivity, Transition, Nanowires, Vortices
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-131716 (URN)10.1088/1367-2630/15/9/095014 (DOI)000324795400004 ()2-s2.0-84885158666 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20131018

Available from: 2013-10-18 Created: 2013-10-17 Last updated: 2017-12-06Bibliographically approved
3. Gain, noise and intermod-ulation in a nonlinear superconducting resonator
Open this publication in new window or tab >>Gain, noise and intermod-ulation in a nonlinear superconducting resonator
(English)Manuscript (preprint) (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-133312 (URN)
Note

QS 2013

Available from: 2013-10-30 Created: 2013-10-30 Last updated: 2013-11-04Bibliographically approved
4. Parametric amplification with weak-link nonlinearity in superconducting microresonators
Open this publication in new window or tab >>Parametric amplification with weak-link nonlinearity in superconducting microresonators
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2009 (English)In: Nobel Symposium 141: Qubits for Future Quantum Information; Gothenburg; 25 May 2009 through 28 May 2009, 2009Conference paper, Published paper (Refereed)
Abstract [en]

Nonlinear kinetic inductance in a high Q superconducting coplanarwaveguide microresonator can cause a bifurcation of the resonance curve. Near thecritical pumping power and frequency for bifurcation, large parametric gain is observedfor signals in the frequency band near resonance. We show experimental results onsignal and intermodulation gain which are well described by a theory of the parametricamplification based on a Kerr nonlinearity. Phase dependent gain, or signal squeezing,is verified with a homodyne detection scheme.

Series
Physica Scripta T, ISSN 0031-8949, E-ISSN 1402-4896
Keyword
Nonlinear oscillators, Parametric amplification
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-11556 (URN)10.1088/0031-8949/2009/T137/014019 (DOI)000272834700020 ()2-s2.0-77952866472 (Scopus ID)
Conference
141st Nobel Symposium on Qubits for Future Quantum Information, Gothenburg, Sweden, May 25-28, 2009
Note

Uppdaterad från manuskript till konferensbidrag: 20100812 QC 20100812

Available from: 2009-11-20 Created: 2009-11-20 Last updated: 2017-03-29Bibliographically approved
5. Nonlinearities and parametric amplification in superconducting coplanar waveguide resonators
Open this publication in new window or tab >>Nonlinearities and parametric amplification in superconducting coplanar waveguide resonators
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2007 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 25, 253509- p.Article in journal (Refereed) Published
Abstract [en]

Experimental investigations of the nonlinear properties of superconducting niobium coplanarwaveguide resonators are reported. The nonlinearity due to a current dependent kinetic inductanceof the center conductor is strong enough to realize bifurcation of the nonlinear oscillator. Whendriven with two frequencies near the threshold for bifurcation, parametric amplification with a gainof +22.4 dB is observed.

Keyword
Nonlinear oscillator, Parametric amplification
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-11550 (URN)10.1063/1.2750520 (DOI)000247468900098 ()2-s2.0-34547281367 (Scopus ID)
Note

QC 20100812

Available from: 2009-11-20 Created: 2009-11-19 Last updated: 2017-12-12Bibliographically approved

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