High critical temperature superconductor Josephson junctions for quantum circuit applications

Gustafsson, David; Cedergren, Karin; Nawaz, Shahid; Virk, Mudassar Mumtaz; Pettersson, Henrik; Olsson, Eva; Lombardi, Floriana

doi:10.1088/0031-8949/2009/t137/014006

Cited by 4 publications

(10 citation statements)

References 22 publications

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“…From the unloaded quality factor Q 0 2000 and the resonator frequency f 0 5 GHz we obtain the resonator photon decay rate ξ = f 0 /Q 0 2.5 MHz. An upper bound of the relaxation rate of a YBCO Josephson junction based phase qubit, which should be comparable to the one of a transmon qubit, was estimated to be γ 25 MHz [7], [28]- [30]. This value results in a dephasing time (T 2 40 ns) much lower than in LTS JJ-based quantum circuits, where values of up to 100 μs have been observed [31].…”

Section: Resultsmentioning

confidence: 87%

“…The possibility of using concepts and designs of superconducting artificial atoms in the so-called transmon configuration [6] to study the low energy excitation spectra of HTS has been discussed in ref. [7]. The transmon consists of a capacitively shunted nano Josephson junction embedded in a coplanar waveguide resonator.…”

Section: Introductionmentioning

confidence: 99%

“…Following the discussion in ref. [7] with the choice of a frequency of 5 GHz and a ratio E j /E c = 100, we would then need I c 40 nA and C Σ 50 fF. Such values are feasible by means of YBCO biepitaxial Josephson nanojunctions [7].…”

Section: Introductionmentioning

confidence: 99%

“…[7] with the choice of a frequency of 5 GHz and a ratio E j /E c = 100, we would then need I c 40 nA and C Σ 50 fF. Such values are feasible by means of YBCO biepitaxial Josephson nanojunctions [7]. High quality YBCO nano-junctions have been recently obtained implementing the biepitaxial technique using a (La 0.3 Sr 0.7 )(Al 0.65 Ta 0.35 )O 3 (LSAT) substrate in combination with a CeO 2 seed layer making them suitable for the realization of a YBCO transmon [11], [12].…”

Section: Introductionmentioning

confidence: 99%

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Microwave Losses in YBCO Coplanar Waveguide Resonators at Low Power and Millikelvin Range

Arzeo

Lombardi

2015

IEEE Trans. Appl. Supercond.

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We have investigated the temperature dependence of microwave losses in the low-power limit and millikelvin temperature range of a thin-film YBa 2 Cu 3 O 7−x (YBCO) λ/2 coplanar waveguide resonator patterned on a (La 0.3 Sr 0.7 ) (Al 0.65 Ta 0.35 )O 3 (LSAT) substrate covered by a CeO 2 seed layer. The unloaded quality factor is mainly governed by the surface resistance of the YBCO film and the dielectric losses caused by resonant absorption due to a bath of two-level fluctuators in the dielectrics. The value of the unloaded quality factor at 20 mK and low power, i.e., Q 0 2000, allows for the realization of YBCO microwave quantum circuits implementing biepitaxial grain-boundary Josephson junctions.Index Terms-Dielectric losses, high critical temperature supreconductors, superconducting microwave devices, superconducting thin films, surface resistance, yttrium barium copper oxide (YBCO).

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Section: Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Microwave Losses in YBCO Coplanar Waveguide Resonators at Low Power and Millikelvin Range

Arzeo

Lombardi

2015

IEEE Trans. Appl. Supercond.

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“…(Bauch et al, 2005) and energy level quantization have been observed in HTS-based Josephson junctions , definitively opening up the way to novel quantum systems based on the HTS d-wave symmetry. This unconventional order parameter can be used to create naturally degenerate two-level systems offering significant advantages for quantum circuit applications (Amin et al, 2005) and to study basic physics in previously inaccessible regimes (Bauch et al, 2009). Over the past few years much progress has been achieved in the field of quantum computation and a number of groups have demonstrated that it is possible to fabricate and entangle solid state qubits (Yamamoto et al, 2003;Majer et al, 2007).…”

Section: Quantum Circuit Applications: Hts Squids As 'Silent' Quantummentioning

confidence: 99%

d-Wave YBCO dc superconductive quantum interference devices (dc SQUIDs)

Lombardi

2011

High-Temperature Superconductors

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Noise properties of nanoscale YBa2Cu3O7−δJosephson

Gustafsson

Lombardi

2011

Phys. Rev. B

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We present electric noise measurements of nanoscale biepitaxial YBa 2 Cu 3 O 7−δ (YBCO) Josephson junctions fabricated by two different lithographic methods. The first (conventional) technique defines the junctions directly by ion milling etching through an amorphous carbon mask. The second (soft patterning) method makes use of the phase competition between the superconducting YBCO (Y123) and the insulating Y 2 BaCuO 5 (Y211) phase at the grain boundary interface on MgO (110) substrates. The voltage noise properties of the two methods are compared in this study. For all junctions (having a thickness of 100 nm and widths of 250-500 nm), we see a significant amount of individual charge traps. We have extracted an approximate value for the effective area of the charge traps from the noise data. From the noise measurements, we infer that the soft-patterned junctions with a grain-boundary (GB) interface manifesting a large c-axis tunneling component have a uniform barrier and a superconductor-insulator-superconductor (SIS) -like behavior. The noise properties of soft-patterned junctions having a GB interface dominated by transport parallel to the ab planes are in accordance with a resonant tunneling barrier model. The conventionally patterned junctions, instead, have suppressed superconducting transport channels with an area much less than the nominal junction area. These findings are important for the implementation of nanosized Josephson junctions in quantum circuits.

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High critical temperature superconductor Josephson junctions for quantum circuit applications

Cited by 4 publications

References 22 publications

Microwave Losses in YBCO Coplanar Waveguide Resonators at Low Power and Millikelvin Range

Microwave Losses in YBCO Coplanar Waveguide Resonators at Low Power and Millikelvin Range

d-Wave YBCO dc superconductive quantum interference devices (dc SQUIDs)

Noise properties of nanoscale YBa2Cu3O7−δJosephson

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