1
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Eriksson AM, Sépulcre T, Kervinen M, Hillmann T, Kudra M, Dupouy S, Lu Y, Khanahmadi M, Yang J, Castillo-Moreno C, Delsing P, Gasparinetti S. Universal control of a bosonic mode via drive-activated native cubic interactions. Nat Commun 2024; 15:2512. [PMID: 38509084 PMCID: PMC10954688 DOI: 10.1038/s41467-024-46507-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/29/2024] [Indexed: 03/22/2024] Open
Abstract
Linear bosonic modes offer a hardware-efficient alternative for quantum information processing but require access to some nonlinearity for universal control. The lack of nonlinearity in photonics has led to encoded measurement-based quantum computing, which relies on linear operations but requires access to resourceful ('nonlinear') quantum states, such as cubic phase states. In contrast, superconducting microwave circuits offer engineerable nonlinearities but suffer from static Kerr nonlinearity. Here, we demonstrate universal control of a bosonic mode composed of a superconducting nonlinear asymmetric inductive element (SNAIL) resonator, enabled by native nonlinearities in the SNAIL element. We suppress static nonlinearities by operating the SNAIL in the vicinity of its Kerr-free point and dynamically activate nonlinearities up to third order by fast flux pulses. We experimentally realize a universal set of generalized squeezing operations, as well as the cubic phase gate, and exploit them to deterministically prepare a cubic phase state in 60 ns. Our results initiate the experimental field of polynomial quantum computing, in the continuous-variables notion originally introduced by Lloyd and Braunstein.
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Affiliation(s)
- Axel M Eriksson
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
| | - Théo Sépulcre
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Mikael Kervinen
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Timo Hillmann
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Marina Kudra
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Simon Dupouy
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Yong Lu
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
- Physikalisches Institut, University of Stuttgart, 70569, Stuttgart, Germany
| | - Maryam Khanahmadi
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Jiaying Yang
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Claudia Castillo-Moreno
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Per Delsing
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Simone Gasparinetti
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
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2
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He XL, Lu Y, Bao DQ, Xue H, Jiang WB, Wang Z, Roudsari AF, Delsing P, Tsai JS, Lin ZR. Fast generation of Schrödinger cat states using a Kerr-tunable superconducting resonator. Nat Commun 2023; 14:6358. [PMID: 37821443 PMCID: PMC10567735 DOI: 10.1038/s41467-023-42057-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 09/28/2023] [Indexed: 10/13/2023] Open
Abstract
Schrödinger cat states, quantum superpositions of macroscopically distinct classical states, are an important resource for quantum communication, quantum metrology and quantum computation. Especially, cat states in a phase space protected against phase-flip errors can be used as a logical qubit. However, cat states, normally generated in three-dimensional cavities and/or strong multi-photon drives, are facing the challenges of scalability and controllability. Here, we present a strategy to generate and preserve cat states in a coplanar superconducting circuit by the fast modulation of Kerr nonlinearity. At the Kerr-free work point, our cat states are passively preserved due to the vanishing Kerr effect. We are able to prepare a 2-component cat state in our chip-based device with a fidelity reaching 89.1% under a 96 ns gate time. Our scheme shows an excellent route to constructing a chip-based bosonic quantum processor.
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Affiliation(s)
- X L He
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - Yong Lu
- 3rd Physikalisches Institut, University of Stuttgart, 70569, Stuttgart, Germany.
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
| | - D Q Bao
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - Hang Xue
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - W B Jiang
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - Z Wang
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - A F Roudsari
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
| | - Per Delsing
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
| | - J S Tsai
- Graduate School of Science, Tokyo University of Science, Shinjuku, Tokyo, 162-0825, Japan
- Center for Quantum Computing, RIKEN, Wako, Saitama, 351-0198, Japan
| | - Z R Lin
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China.
- University of Chinese Academy of Science, 100049, Beijing, China.
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3
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Lin WJ, Lu Y, Wen PY, Cheng YT, Lee CP, Lin KT, Chiang KH, Hsieh MC, Chen CY, Chien CH, Lin JJ, Chen JC, Lin YH, Chuu CS, Nori F, Frisk Kockum A, Lin GD, Delsing P, Hoi IC. Deterministic Loading of Microwaves onto an Artificial Atom Using a Time-Reversed Waveform. Nano Lett 2022; 22:8137-8142. [PMID: 36200986 PMCID: PMC9615994 DOI: 10.1021/acs.nanolett.2c02578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/28/2022] [Indexed: 06/16/2023]
Abstract
Loading quantum information deterministically onto a quantum node is an important step toward a quantum network. Here, we demonstrate that coherent-state microwave photons with an optimal temporal waveform can be efficiently loaded onto a single superconducting artificial atom in a semi-infinite one-dimensional (1D) transmission-line waveguide. Using a weak coherent state (the number of photons (N) contained in the pulse ≪1) with an exponentially rising waveform, whose time constant matches the decoherence time of the artificial atom, we demonstrate a loading efficiency of 94.2% ± 0.7% from 1D semifree space to the artificial atom. The high loading efficiency is due to time-reversal symmetry: the overlap between the incoming wave and the time-reversed emitted wave is up to 97.1% ± 0.4%. Our results open up promising applications in realizing quantum networks based on waveguide quantum electrodynamics.
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Affiliation(s)
- Wei-Ju Lin
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Yong Lu
- Department
of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96Gothenburg, Sweden
- 3rd
Institute of Physics, IQST, and Research Centre SCoPE, University of Stuttgart, Stuttgart70049, Germany
| | - Ping Yi Wen
- Department
of Physics, National Chung Cheng University, Chiayi621301, Taiwan
| | - Yu-Ting Cheng
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Ching-Ping Lee
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Kuan Ting Lin
- CQSE,
Department of Physics, National Taiwan University, Taipei10617, Taiwan
| | - Kuan Hsun Chiang
- Department
of Physics, National Central University, Jhongli32001, Taiwan
| | - Ming Che Hsieh
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Ching-Yeh Chen
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Chin-Hsun Chien
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Jia Jhan Lin
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Jeng-Chung Chen
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
- Center
for Quantum Technology, National Tsing Hua
University, Hsinchu30013, Taiwan
| | - Yen Hsiang Lin
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
- Center
for Quantum Technology, National Tsing Hua
University, Hsinchu30013, Taiwan
| | - Chih-Sung Chuu
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
- Center
for Quantum Technology, National Tsing Hua
University, Hsinchu30013, Taiwan
| | - Franco Nori
- Theoretical
Quantum Physics Laboratory, RIKEN Cluster
for Pioneering Research, Wako-shi, Saitama351-0198, Japan
- Physics
Department, The University of Michigan, Ann Arbor, Michigan48109-1040, United States
| | - Anton Frisk Kockum
- Department
of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96Gothenburg, Sweden
| | - Guin Dar Lin
- CQSE,
Department of Physics, National Taiwan University, Taipei10617, Taiwan
- Physics
Division, National Center for Theoretical
Sciences, Taipei10617, Taiwan
- Trapped-Ion
Quantum Computing Laboratory, Hon Hai Research
Institute, Taipei11492, Taiwan
| | - Per Delsing
- Department
of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96Gothenburg, Sweden
| | - Io-Chun Hoi
- Department
of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
- Department
of Physics, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR999077, China
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4
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Tholén MO, Borgani R, Di Carlo GR, Bengtsson A, Križan C, Kudra M, Tancredi G, Bylander J, Delsing P, Gasparinetti S, Haviland DB. Measurement and control of a superconducting quantum processor with a fully integrated radio-frequency system on a chip. Rev Sci Instrum 2022; 93:104711. [PMID: 36319392 DOI: 10.1063/5.0101398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
We describe a digital microwave platform called Presto, designed for measurement and control of multiple quantum bits (qubits) and based on the third-generation radio-frequency system on a chip. Presto uses direct digital synthesis to create signals up to 9 GHz on 16 synchronous output ports, while synchronously analyzing responses on 16 input ports. Presto has 16 DC-bias outputs, four inputs and four outputs for digital triggers or markers, and two continuous-wave outputs for synthesizing frequencies up to 15 GHz. Scaling to a large number of qubits is enabled through deterministic synchronization of multiple Presto units. A Python application programming interface configures a firmware for synthesis and analysis of pulses, coordinated by an event sequencer. The analysis integrates template matching (matched filtering) and low-latency (184-254 ns) feedback to enable a wide range of multi-qubit experiments. We demonstrate Presto's capabilities with experiments on a sample consisting of two superconducting qubits connected via a flux-tunable coupler. We show single-shot readout and active reset of a single qubit; randomized benchmarking of single-qubit gates showing 99.972% fidelity, limited by the coherence time of the qubit; and calibration of a two-qubit iSWAP gate.
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Affiliation(s)
- Mats O Tholén
- Nanostructure Physics, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden
| | - Riccardo Borgani
- Nanostructure Physics, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden
| | | | - Andreas Bengtsson
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Christian Križan
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Marina Kudra
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Giovanna Tancredi
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Jonas Bylander
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Per Delsing
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Simone Gasparinetti
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - David B Haviland
- Nanostructure Physics, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden
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5
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Lu Y, Strandberg I, Quijandría F, Johansson G, Gasparinetti S, Delsing P. Propagating Wigner-Negative States Generated from the Steady-State Emission of a Superconducting Qubit. Phys Rev Lett 2021; 126:253602. [PMID: 34241509 DOI: 10.1103/physrevlett.126.253602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
We experimentally demonstrate the steady-state generation of propagating Wigner-negative states from a continuously driven superconducting qubit. We reconstruct the Wigner function of the radiation emitted into propagating modes defined by their temporal envelopes, using digital filtering. For an optimized temporal filter, we observe a large Wigner logarithmic negativity, in excess of 0.08, in agreement with theory. The fidelity between the theoretical predictions and the states generated experimentally is up to 99%, reaching state-of-the-art realizations in the microwave frequency domain. Our results provide a new way to generate and control nonclassical states, and may enable promising applications such as quantum networks and quantum computation based on waveguide quantum electrodynamics.
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Affiliation(s)
- Yong Lu
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Ingrid Strandberg
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Fernando Quijandría
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Göran Johansson
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Simone Gasparinetti
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Per Delsing
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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6
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Andersson G, Ekström MK, Delsing P. Electromagnetically Induced Acoustic Transparency with a Superconducting Circuit. Phys Rev Lett 2020; 124:240402. [PMID: 32639822 DOI: 10.1103/physrevlett.124.240402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
We report the observation of electromagnetically induced transparency (EIT) of a mechanical field, where a superconducting artificial atom is coupled to a 1D-transmission line for surface acoustic waves. An electromagnetic microwave drive is used as the control field, rendering the superconducting transmon qubit transparent to the acoustic probe beam. The strong frequency dependence of the acoustic coupling enables EIT in a ladder configuration due to the suppressed relaxation of the upper level. Our results show that superconducting circuits can be engineered to interact with acoustic fields in parameter regimes not readily accessible to purely electromagnetic systems.
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Affiliation(s)
- Gustav Andersson
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, Kemivägen 9 SE-41296 Göteborg, Sweden
| | - Maria K Ekström
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, Kemivägen 9 SE-41296 Göteborg, Sweden
| | - Per Delsing
- Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, Kemivägen 9 SE-41296 Göteborg, Sweden
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7
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Schneider BH, Bengtsson A, Svensson IM, Aref T, Johansson G, Bylander J, Delsing P. Observation of Broadband Entanglement in Microwave Radiation from a Single Time-Varying Boundary Condition. Phys Rev Lett 2020; 124:140503. [PMID: 32338986 DOI: 10.1103/physrevlett.124.140503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 02/28/2020] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
Entangled pairs of microwave photons are commonly produced in the narrow frequency band of a resonator, which represents a modified vacuum density of states. We generate and investigate the entanglement of a stream of photon pairs, generated in a semi-infinite broadband transmission line, terminated by a superconducting quantum interference device (SQUID). A weak pump signal modulates the SQUID inductance, resulting in a single time-varying boundary condition, and we detect all four quadratures of the microwave radiation emitted at two different frequencies separated by 0.7 GHz. Power calibration is done in situ, and we find positive logarithmic negativity and two-mode squeezing below the vacuum in the observed radiation, indicating entanglement.
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Affiliation(s)
- B H Schneider
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - A Bengtsson
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - I M Svensson
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - T Aref
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - G Johansson
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Jonas Bylander
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - P Delsing
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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8
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Wen PY, Lin KT, Kockum AF, Suri B, Ian H, Chen JC, Mao SY, Chiu CC, Delsing P, Nori F, Lin GD, Hoi IC. Large Collective Lamb Shift of Two Distant Superconducting Artificial Atoms. Phys Rev Lett 2019; 123:233602. [PMID: 31868475 DOI: 10.1103/physrevlett.123.233602] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Indexed: 06/10/2023]
Abstract
Virtual photons can mediate interaction between atoms, resulting in an energy shift known as a collective Lamb shift. Observing the collective Lamb shift is challenging, since it can be obscured by radiative decay and direct atom-atom interactions. Here, we place two superconducting qubits in a transmission line terminated by a mirror, which suppresses decay. We measure a collective Lamb shift reaching 0.8% of the qubit transition frequency and twice the transition linewidth. We also show that the qubits can interact via the transmission line even if one of them does not decay into it.
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Affiliation(s)
- P Y Wen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Center for Quantum Technology, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - K-T Lin
- CQSE, Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - A F Kockum
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
| | - B Suri
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bengaluru 560012, India
| | - H Ian
- Institute of Applied Physics and Materials Engineering, University of Macau, Macau, China
- UMacau Zhuhai Research Institute, Zhuhai, Guangdong 519031, China
| | - J C Chen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Center for Quantum Technology, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - S Y Mao
- Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30013, Taiwan
| | - C C Chiu
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - P Delsing
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - F Nori
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - G-D Lin
- CQSE, Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - I-C Hoi
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Center for Quantum Technology, National Tsing Hua University, Hsinchu 30013, Taiwan
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9
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Svensson IM, Pierre M, Simoen M, Wustmann W, Krantz P, Bengtsson A, Johansson G, Bylander J, Shumeiko V, Delsing P. Microwave photon generation in a doubly tunable superconducting resonator. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1742-6596/969/1/012146] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Nik S, Krantz P, Zeng L, Greibe T, Pettersson H, Gustafsson S, Delsing P, Olsson E. Correlation between Al grain size, grain boundary grooves and local variations in oxide barrier thickness of Al/AlOx/Al tunnel junctions by transmission electron microscopy. Springerplus 2016; 5:1067. [PMID: 27462515 PMCID: PMC4943912 DOI: 10.1186/s40064-016-2418-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 05/25/2016] [Indexed: 12/02/2022]
Abstract
A thickness variation of
only one Ångström makes a significant difference in the current through a tunnel junction due to the exponential thickness dependence of the current. It is thus important to achieve a uniform thickness along the barrier to enhance, for example, the sensitivity and speed of single electron transistors based on the tunnel junctions. Here, we have observed that grooves at Al grain boundaries are associated with a local increase of tunnel barrier thickness. The uniformity of the barrier thickness along the tunnel junction thus increases with increasing Al grain size. We have studied the effect of oxidation time, partial oxygen pressure and also temperature during film growth on the grain size. The implications are that the uniformity improves with higher temperature during film growth.
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Affiliation(s)
- Samira Nik
- Department of Applied Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Philip Krantz
- Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Lunjie Zeng
- Department of Applied Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Tine Greibe
- Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Henrik Pettersson
- Department of Applied Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Stefan Gustafsson
- Department of Applied Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Per Delsing
- Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Eva Olsson
- Department of Applied Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
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11
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Krantz P, Bengtsson A, Simoen M, Gustavsson S, Shumeiko V, Oliver WD, Wilson CM, Delsing P, Bylander J. Single-shot read-out of a superconducting qubit using a Josephson parametric oscillator. Nat Commun 2016; 7:11417. [PMID: 27156732 PMCID: PMC4865746 DOI: 10.1038/ncomms11417] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 03/24/2016] [Indexed: 11/10/2022] Open
Abstract
We propose and demonstrate a read-out technique for a superconducting qubit by dispersively coupling it with a Josephson parametric oscillator. We employ a tunable quarter wavelength superconducting resonator and modulate its resonant frequency at twice its value with an amplitude surpassing the threshold for parametric instability. We map the qubit states onto two distinct states of classical parametric oscillation: one oscillating state, with 185±15 photons in the resonator, and one with zero oscillation amplitude. This high contrast obviates a following quantum-limited amplifier. We demonstrate proof-of-principle, single-shot read-out performance, and present an error budget indicating that this method can surpass the fidelity threshold required for quantum computing.
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Affiliation(s)
- Philip Krantz
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Gothenburg, Sweden
| | - Andreas Bengtsson
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Gothenburg, Sweden
| | - Michaël Simoen
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Gothenburg, Sweden
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Vitaly Shumeiko
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Gothenburg, Sweden
| | - W. D. Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - C. M. Wilson
- Institute of Quantum Computing, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
| | - Per Delsing
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Gothenburg, Sweden
| | - Jonas Bylander
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Gothenburg, Sweden
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12
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Bruschi DE, Sabín C, Kok P, Johansson G, Delsing P, Fuentes I. Towards universal quantum computation through relativistic motion. Sci Rep 2016; 6:18349. [PMID: 26860584 PMCID: PMC4748225 DOI: 10.1038/srep18349] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/16/2015] [Indexed: 11/25/2022] Open
Abstract
We show how to use relativistic motion to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimentally using superconducting circuits where tuneable boundary conditions correspond to mirrors moving with velocities close to the speed of light. In particular, we propose the generation of a quadripartite square cluster state as a first example that can be readily implemented in the laboratory. Since cluster states are universal resources for universal one-way quantum computation, our results pave the way for relativistic quantum computation schemes.
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Affiliation(s)
- David Edward Bruschi
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.,School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
| | - Carlos Sabín
- Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid, Spain
| | - Pieter Kok
- Department of Physics &Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
| | - Göran Johansson
- Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Göteborg, Sweden
| | - Per Delsing
- Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Göteborg, Sweden
| | - Ivette Fuentes
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
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13
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Pourkabirian A, Gustafsson MV, Johansson G, Clarke J, Delsing P. Nonequilibrium probing of two-level charge fluctuators using the step response of a single-electron transistor. Phys Rev Lett 2014; 113:256801. [PMID: 25554902 DOI: 10.1103/physrevlett.113.256801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Indexed: 06/04/2023]
Abstract
We report a new method to study two-level fluctuators (TLFs) by measuring the offset charge induced after applying a sudden step voltage to the gate electrode of a single-electron transistor. The offset charge is measured for more than 20 h for samples made on three different substrates. We find that the offset charge drift follows a logarithmic increase over 4 orders of magnitude in time and that the logarithmic slope increases linearly with the step voltage. The charge drift is independent of temperature, ruling out thermally activated TLFs and demonstrating that the charge fluctuations involve tunneling. These observations are in agreement with expectations for an ensemble of TLFs driven out of equilibrium. From our model, we extract the density of TLFs assuming either a volume density or a surface density.
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Affiliation(s)
- A Pourkabirian
- Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
| | - M V Gustafsson
- Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
| | - G Johansson
- Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
| | - J Clarke
- Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden and Department of Physics, University of California, Berkeley, California 94720, USA
| | - P Delsing
- Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
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14
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Abstract
Quantum information can be stored in micromechanical resonators, encoded as quanta of vibration known as phonons. The vibrational motion is then restricted to the stationary eigenmodes of the resonator, which thus serves as local storage for phonons. In contrast, we couple propagating phonons to an artificial atom in the quantum regime and reproduce findings from quantum optics, with sound taking over the role of light. Our results highlight the similarities between phonons and photons but also point to new opportunities arising from the characteristic features of quantum mechanical sound. The low propagation speed of phonons should enable new dynamic schemes for processing quantum information, and the short wavelength allows regimes of atomic physics to be explored that cannot be reached in photonic systems.
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Affiliation(s)
- Martin V Gustafsson
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Göteborg, Sweden. Department of Chemistry, Columbia University, NWC Building, 550 West 120th Street, New York, NY 10027, USA.
| | - Thomas Aref
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Göteborg, Sweden
| | - Anton Frisk Kockum
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Göteborg, Sweden
| | - Maria K Ekström
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Göteborg, Sweden
| | - Göran Johansson
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Göteborg, Sweden
| | - Per Delsing
- Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-41296 Göteborg, Sweden.
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15
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Felicetti S, Sanz M, Lamata L, Romero G, Johansson G, Delsing P, Solano E. Dynamical Casimir effect entangles artificial atoms. Phys Rev Lett 2014; 113:093602. [PMID: 25215982 DOI: 10.1103/physrevlett.113.093602] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Indexed: 06/03/2023]
Abstract
We show that the physics underlying the dynamical Casimir effect may generate multipartite quantum correlations. To achieve it, we propose a circuit quantum electrodynamics scenario involving superconducting quantum interference devices, cavities, and superconducting qubits, also called artificial atoms. Our results predict the generation of highly entangled states for two and three superconducting qubits in different geometric configurations with realistic parameters. This proposal paves the way for a scalable method of multipartite entanglement generation in cavity networks through dynamical Casimir physics.
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Affiliation(s)
- S Felicetti
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - M Sanz
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - L Lamata
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - G Romero
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - G Johansson
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - P Delsing
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - E Solano
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain and IKERBASQUE, Basque Foundation for Science, Alameda Urquijo 36, 48011 Bilbao, Spain
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16
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Abay S, Persson D, Nilsson H, Xu HQ, Fogelström M, Shumeiko V, Delsing P. Quantized conductance and its correlation to the supercurrent in a nanowire connected to superconductors. Nano Lett 2013; 13:3614-3617. [PMID: 23898893 DOI: 10.1021/nl4014265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report conductance and supercurrent of InAs nanowires coupled to Al-superconducting electrodes with short channel lengths and good Ohmic contacts. The nanowires are suspended 15 nm above a local gate electrode. The charge density in the nanowires can be controlled by a small change in the gate voltage. For large negative gate voltages, the number of conducting channels is reduced gradually, and we observe a stepwise decrease of both conductance and critical current before the conductance vanishes completely.
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Affiliation(s)
- Simon Abay
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, Göteborg, Sweden.
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17
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Hoi IC, Kockum AF, Palomaki T, Stace TM, Fan B, Tornberg L, Sathyamoorthy SR, Johansson G, Delsing P, Wilson CM. Giant cross-Kerr effect for propagating microwaves induced by an artificial atom. Phys Rev Lett 2013; 111:053601. [PMID: 23952397 DOI: 10.1103/physrevlett.111.053601] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 03/21/2013] [Indexed: 06/02/2023]
Abstract
We investigate the effective interaction between two microwave fields, mediated by a transmon-type superconducting artificial atom which is strongly coupled to a coplanar transmission line. The interaction between the fields and atom produces an effective cross-Kerr coupling. We demonstrate average cross-Kerr phase shifts of up to 20 degrees per photon with both coherent microwave fields at the single-photon level. Our results provide an important step toward quantum applications with propagating microwave photons.
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Affiliation(s)
- Io-Chun Hoi
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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18
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Fan B, Kockum AF, Combes J, Johansson G, Hoi IC, Wilson CM, Delsing P, Milburn GJ, Stace TM. Breakdown of the cross-Kerr scheme for photon counting. Phys Rev Lett 2013; 110:053601. [PMID: 23414018 DOI: 10.1103/physrevlett.110.053601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Indexed: 06/01/2023]
Abstract
We show, in the context of single-photon detection, that an atomic three-level model for a transmon in a transmission line does not support the predictions of the nonlinear polarizability model known as the cross-Kerr effect. We show that the induced displacement of a probe in the presence or absence of a single photon in the signal field, cannot be resolved above the quantum noise in the probe. This strongly suggests that cross-Kerr media are not suitable for photon counting or related single-photon applications. Our results are presented in the context of a transmon in a one-dimensional microwave waveguide, but the conclusions also apply to optical systems.
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Affiliation(s)
- Bixuan Fan
- Center for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia
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19
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Abay S, Nilsson H, Wu F, Xu HQ, Wilson CM, Delsing P. High critical-current superconductor-InAs nanowire-superconductor junctions. Nano Lett 2012; 12:5622-5625. [PMID: 23030250 DOI: 10.1021/nl302740f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the fabrication of InAs nanowires coupled to superconducting leads with high critical current and widely tunable conductance. We implemented a double lift-off nanofabrication method to get very short nanowire devices with Ohmic contacts. We observe very high critical currents of up to 800 nA in a wire with a diameter of 80 nm. The current-voltage characteristics of longer and suspended nanowires display either Coulomb blockade or supercurrent depending on a local gate voltage, combining different regimes of transport in a single device.
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Affiliation(s)
- Simon Abay
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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20
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Hoi IC, Palomaki T, Lindkvist J, Johansson G, Delsing P, Wilson CM. Generation of nonclassical microwave states using an artificial atom in 1D open space. Phys Rev Lett 2012; 108:263601. [PMID: 23004976 DOI: 10.1103/physrevlett.108.263601] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Indexed: 06/01/2023]
Abstract
We have embedded an artificial atom, a superconducting transmon qubit, in a 1D open space and investigated the scattering properties of an incident microwave coherent state. By studying the statistics of the reflected and transmitted fields, we demonstrate that the scattered states can be nonclassical. In particular, by measuring the second-order correlation function, g((2)), we show photon antibunching in the reflected field and superbunching in the transmitted field. We also compare the elastically and inelastically scattered fields using both phase-sensitive and phase-insensitive measurements.
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Affiliation(s)
- Io-Chun Hoi
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-41296, Göteborg, Sweden
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21
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Hoi IC, Wilson CM, Johansson G, Palomaki T, Peropadre B, Delsing P. Demonstration of a single-photon router in the microwave regime. Phys Rev Lett 2011; 107:073601. [PMID: 21902392 DOI: 10.1103/physrevlett.107.073601] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/04/2011] [Indexed: 05/31/2023]
Abstract
We have embedded an artificial atom, a superconducting transmon qubit, in an open transmission line and investigated the strong scattering of incident microwave photons (∼6 GHz). When an input coherent state, with an average photon number N≪1 is on resonance with the artificial atom, we observe extinction of up to 99.6% in the forward propagating field. We use two-tone spectroscopy to study scattering from excited states and we observe electromagnetically induced transparency (EIT). We then use EIT to make a single-photon router, where we can control to what output port an incoming signal is delivered. The maximum on-off ratio is around 99% with a rise and fall time on the order of nanoseconds, consistent with theoretical expectations. The router can easily be extended to have multiple output ports and it can be viewed as a rudimentary quantum node, an important step towards building quantum information networks.
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Affiliation(s)
- Io-Chun Hoi
- MC2, Chalmers University of Technology, Göteborg, Sweden
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22
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Greibe T, Stenberg MPV, Wilson CM, Bauch T, Shumeiko VS, Delsing P. Are "pinholes" the cause of excess current in superconducting tunnel junctions? A study of Andreev current in highly resistive junctions. Phys Rev Lett 2011; 106:097001. [PMID: 21405645 DOI: 10.1103/physrevlett.106.097001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Indexed: 05/30/2023]
Abstract
In highly resistive superconducting tunnel junctions, excess subgap current is usually observed and is often attributed to microscopic pinholes in the tunnel barrier. We have studied the subgap current in superconductor-insulator-superconductor (SIS) and superconductor-insulator-normal-metal (SIN) junctions. In Al/AlO(x)/Al junctions, we observed a decrease of 2 orders of magnitude in the current upon the transition from the SIS to the SIN regime, where it then matched theory. In Al/AlO(x)/Cu junctions, we also observed generic features of coherent diffusive Andreev transport in a junction with a homogenous barrier. We use the quasiclassical Keldysh-Green function theory to quantify single- and two-particle tunneling and find good agreement with experiment over 2 orders of magnitude in transparency. We argue that our observations rule out pinholes as the origin of the excess current.
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Affiliation(s)
- Tine Greibe
- Department of Microelectronics and Nanoscience, Chalmers University of Technology, Göteborg, Sweden
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23
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Wilson CM, Duty T, Sandberg M, Persson F, Shumeiko V, Delsing P. Photon generation in an electromagnetic cavity with a time-dependent boundary. Phys Rev Lett 2010; 105:233907. [PMID: 21231466 DOI: 10.1103/physrevlett.105.233907] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Revised: 11/03/2010] [Indexed: 05/30/2023]
Abstract
We report the observation of photon generation in a microwave cavity with a time-dependent boundary condition. Our system is a microfabricated quarter-wave coplanar waveguide cavity. The electrical length of the cavity is varied by using the tunable inductance of a superconducting quantum interference device. It is measured at a temperature significantly less than the resonance frequency. When the length is modulated at approximately twice the static resonance frequency, spontaneous parametric oscillations of the cavity field are observed. Time-resolved measurements of the dynamical state of the cavity show multiple stable states. The behavior is well described by theory. Our results may be considered a preliminary step towards demonstrating the dynamical Casimir effect.
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Affiliation(s)
- C M Wilson
- Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
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24
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Persson F, Wilson CM, Sandberg M, Johansson G, Delsing P. Excess dissipation in a single-electron box: the Sisyphus resistance. Nano Lett 2010; 10:953-957. [PMID: 20155965 DOI: 10.1021/nl903887x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present measurements of the ac response of a single-electron box (SEB). We apply a radio frequency signal with a frequency larger than the tunneling rate and drive the system out of equilibrium. We observe much more dissipation in the SEB then one would expect from a simple circuit model. We can explain this in terms of a mechanism that we call the Sisyphus resistance. The Sisyphus resistance has a strong gate dependence which can be used for electrometery applications.
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Affiliation(s)
- F Persson
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Goteborg, Sweden.
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25
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Nilsson HA, Duty T, Abay S, Wilson C, Wagner JB, Thelander C, Delsing P, Samuelson L. A radio frequency single-electron transistor based on an InAs/InP heterostructure nanowire. Nano Lett 2008; 8:872-875. [PMID: 18302328 DOI: 10.1021/nl0731062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We demonstrate radio frequency single-electron transistors fabricated from epitaxially grown InAs/InP heterostructure nanowires. Two sets of double-barrier wires with different barrier thicknesses were grown. The wires were suspended 15 nm above a metal gate electrode. Electrical measurements on a high-resistance nanowire showed regularly spaced Coulomb oscillations at a gate voltage from -0.5 to at least 1.8 V. The charge sensitivity was measured to 32 microe rms Hz(-1/2) at 1.5 K. A low-resistance single-electron transistor showed regularly spaced oscillations only in a small gate-voltage region just before carrier depletion. This device had a charge sensitivity of 2.5 microe rms Hz(-1/2). At low frequencies this device showed a typical 1/f noise behavior, with a level extrapolated to 300 microe rms Hz(-1/2) at 10 Hz.
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Affiliation(s)
- Henrik A Nilsson
- Solid State Physics, Lund University, Box 118, S-221 00, Lund, Sweden.
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26
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Wilson CM, Duty T, Persson F, Sandberg M, Johansson G, Delsing P. Coherence times of dressed states of a superconducting qubit under extreme driving. Phys Rev Lett 2007; 98:257003. [PMID: 17678048 DOI: 10.1103/physrevlett.98.257003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Indexed: 05/16/2023]
Abstract
We measure longitudinal dressed states of a superconducting qubit, the single Cooper-pair box, and an intense microwave field. The dressed states represent the hybridization of the qubit and photon degrees of freedom and appear as avoided level crossings in the combined energy diagram. By embedding the circuit in an rf oscillator, we directly probe the dressed states. We measure their dressed gap as a function of photon number and microwave amplitude, finding good agreement with theory. In addition, we extract the relaxation and dephasing rates of these states.
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Affiliation(s)
- C M Wilson
- Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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27
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Brenning HTA, Kubatkin SE, Erts D, Kafanov SG, Bauch T, Delsing P. A single electron transistor on an atomic force microscope probe. Nano Lett 2006; 6:937-41. [PMID: 16683829 DOI: 10.1021/nl052526t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We report fabrication as well as proof-of-concept experiments of a noninvasive sensor of weak nanoscale electric fields. The sensor is a single electron transistor (SET) placed at the tip of a noncontact atomic force microscope (AFM). This is a general technology to make any nanometer-sized lithography pattern at edges or tips of a cantilever. The height control of the AFM allows the SET to hover a few nanometers above the substrate, improving both the electric field sensitivity and lateral resolution of the electrometer. Our AFM-SET sensor is prepared by a scalable technology. It means that the probe can be routinely fabricated and replaced, if broken.
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Affiliation(s)
- Henrik T A Brenning
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
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28
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Abstract
Here we present the direct observation of macroscopic quantum properties in an all high-critical-temperature superconductor d-wave Josephson junction. Although dissipation caused by low-energy excitations is expected to strongly suppress macroscopic quantum effects, we demonstrate energy level quantization in our d-wave Josephson junction. The result indicates that the role of dissipation mechanisms in high-temperature superconductors has to be revised, and it may also have consequences for the class of solid-state "quiet" quantum bits with superior coherence time.
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Affiliation(s)
- Thilo Bauch
- Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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29
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Duty T, Johansson G, Bladh K, Gunnarsson D, Wilson C, Delsing P. Observation of quantum capacitance in the Cooper-pair transistor. Phys Rev Lett 2005; 95:206807. [PMID: 16384086 DOI: 10.1103/physrevlett.95.206807] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Indexed: 05/05/2023]
Abstract
We have fabricated a Cooper-pair transistor (CPT) with parameters such that for appropriate voltage biases, it behaves essentially like a single Cooper-pair box (SCB). The effective capacitance of a SCB can be defined as the derivative of the induced charge with respect to gate voltage and has two parts, the geometric capacitance, C(geom), and the quantum capacitance C(Q). The latter is due to the level anticrossing caused by the Josephson coupling and is dual to the Josephson inductance. It depends parametrically on the gate voltage and its magnitude may be substantially larger than C(geom). We have detected C(Q) in our CPT, by measuring the in phase and quadrature rf signal reflected from a resonant circuit in which the CPT is embedded. C(Q) can be used as the basis of a charge qubit readout by placing a Cooper-pair box in such a resonant circuit.
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Affiliation(s)
- T Duty
- Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96 Göteborg, Sweden.
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30
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Krasnov VM, Bauch T, Intiso S, Hürfeld E, Akazaki T, Takayanagi H, Delsing P. Collapse of thermal activation in moderately damped Josephson junctions. Phys Rev Lett 2005; 95:157002. [PMID: 16241753 DOI: 10.1103/physrevlett.95.157002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Indexed: 05/05/2023]
Abstract
We study switching current statistics in moderately damped Nb-InAs-Nb and intrinsic Bi2Sr2CaCu2O8+delta) Josephson junctions. A paradoxical collapse of thermal activation with increasing temperature is reported and explained by the interplay of two conflicting consequences of thermal fluctuations, which can both assist in premature escape and help in retrapping back into the stationary state. We analyze the influence of dissipation on the thermal escape by tuning damping with a gate voltage, magnetic field, temperature, and an in situ capacitor.
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Affiliation(s)
- V M Krasnov
- Department of Physics, Stockholm University, Albanova University Center, SE-10691 Stockholm, Sweden
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31
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Bauch T, Lombardi F, Tafuri F, Barone A, Rotoli G, Delsing P, Claeson T. Macroscopic quantum tunneling in d-wave YBa2Cu3O7-delta Josephson junctions. Phys Rev Lett 2005; 94:087003. [PMID: 15783922 DOI: 10.1103/physrevlett.94.087003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2004] [Indexed: 05/24/2023]
Abstract
The escape rate from the zero voltage state in a superconducting Josephson junction (JJ) is determined by the temperature, but it saturates at low temperature due to macroscopic quantum tunneling (MQT). Complications due to d-wave symmetry in a high temperature superconductor, like low energy quasiparticles and an unconventional current-phase relation, may influence the escape rate. We report, for the first time to our knowledge, the observation of MQT in a YBa(2)Cu(3)O(7-delta) grain boundary biepitaxial JJ. This proves that dissipation can be significantly reduced by a proper junction configuration, which is of significance for quantum coherence.
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Affiliation(s)
- T Bauch
- Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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32
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Abstract
The fact that electrical current is carried by individual charges has been known for over 100 years, yet this discreteness has not been directly observed so far. Almost all current measurements involve measuring the voltage drop across a resistor, using Ohm's law, in which the discrete nature of charge does not come into play. However, by sending a direct current through a microelectronic circuit with a chain of islands connected by small tunnel junctions, the individual electrons can be observed one by one. The quantum mechanical tunnelling of single charges in this one-dimensional array is time correlated, and consequently the detected signal has the average frequency f = I/e, where I is the current and e is the electron charge. Here we report a direct observation of these time-correlated single-electron tunnelling oscillations, and show electron counting in the range 5 fA-1 pA. This represents a fundamentally new way to measure extremely small currents, without offset or drift. Moreover, our current measurement, which is based on electron counting, is self-calibrated, as the measured frequency is related to the current only by a natural constant.
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Affiliation(s)
- Jonas Bylander
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
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Lehnert KW, Turek BA, Bladh K, Spietz LF, Gunnarsson D, Delsing P, Schoelkopf RJ. Quantum charge fluctuations and the polarizability of the single-electron box. Phys Rev Lett 2003; 91:106801. [PMID: 14525496 DOI: 10.1103/physrevlett.91.106801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2003] [Indexed: 05/24/2023]
Abstract
We measure the average charge on the island of a single-electron box, with an accuracy of two thousandths of an electron. Thermal fluctuations alone cannot account for the dependence of the average charge on temperature, on external potential, or on the quasiparticle density of states in the metal from which the box is formed. In contrast, we find excellent agreement between these measurements and a theory that treats the quantum fluctuations of charge perturbatively.
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Affiliation(s)
- K W Lehnert
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA.
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Lehnert KW, Bladh K, Spietz LF, Gunnarsson D, Schuster DI, Delsing P, Schoelkopf RJ. Measurement of the excited-state lifetime of a microelectronic circuit. Phys Rev Lett 2003; 90:027002. [PMID: 12570573 DOI: 10.1103/physrevlett.90.027002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2002] [Indexed: 05/24/2023]
Abstract
We demonstrate that a continuously measured microelectronic circuit, the Cooper-pair box measured by a radio-frequency single-electron transistor, approximates a quantum two-level system. We extract the Hamiltonian of the circuit through resonant spectroscopy and measure the excited-state lifetime. The lifetime is more than 10(5) times longer than the inverse transition frequency of the two-level system, even though the measurement is active. This lifetime is also comparable to an estimate of the known upper limit, set by spontaneous emission, for this circuit.
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Affiliation(s)
- K W Lehnert
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA.
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35
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Aassime A, Bladh K, Claeson T, Delsing P, Gunnarsson D. Similarities between single charge and Josephson effects and devices. A fast and sensitive radio frequency single electron transistor. Materials Science and Engineering: C 2002. [DOI: 10.1016/s0928-4931(01)00412-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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36
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Aassime A, Johansson G, Wendin G, Schoelkopf RJ, Delsing P. Radio-frequency single-electron transistor as readout device for qubits: charge sensitivity and backaction. Phys Rev Lett 2001; 86:3376-3379. [PMID: 11327974 DOI: 10.1103/physrevlett.86.3376] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2000] [Indexed: 05/23/2023]
Abstract
We study the radio-frequency single-electron transistor (rf-SET) as a readout device for charge qubits. We measure the charge sensitivity of an rf-SET to be 6.3microe/sqrt[Hz] and evaluate the backaction of the rf-SET on a single Cooper-pair box. This allows us to compare the needed measurement time with the mixing time of the qubit imposed by the measurement. We find that the mixing time can be substantially longer than the measurement time, which would allow readout of the state of the qubit in a single shot measurement.
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Affiliation(s)
- A Aassime
- Microtechnology Center at Chalmers MC2, Department of Microelectronics and Nanoscience, Chalmers University of Technology and Göteborg University, S-412 96, Göteborg, Sweden
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37
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de Haan L, van Raaij B, van den Berg R, Jager M, Houweling P, Stockmann M, Delsing P, Linszen D, Peters B, Wouters L. Preferences for treatment during a first psychotic episode. Eur Psychiatry 2001; 16:83-9. [PMID: 11311171 DOI: 10.1016/s0924-9338(01)00542-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Psychiatric services providing care for patients and their families confronted with a first psychotic episode need to be sensitive towards patients' and families' preferences. Ten patients, ten family members and ten professional caregivers composed a list of 42 preferences in the treatment for a first psychotic episode. In total 99 patients, 100 family members and 263 professional caregivers evaluated these preferences, thus producing an order of priorities. There appears to be considerable agreement among the groups of respondents regarding their top ten priorities, especially concerning information on diagnosis and medication. However, we found important differences between groups of respondents. The results suggest that in psychiatric services great attention should be given to psycho-education and early outpatient intervention.
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Affiliation(s)
- L de Haan
- Adolescent Clinic, Academic Medical Centre, University of Amsterdam, Department of Psychiatry, Postbox 22700, 1100 DE Amsterdam, The Netherlands
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38
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Camarota B, Parage F, Balestro F, Delsing P, Buisson O. Experimental evidence of one-dimensional plasma modes in superconducting thin wires. Phys Rev Lett 2001; 86:480-483. [PMID: 11177860 DOI: 10.1103/physrevlett.86.480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2000] [Indexed: 05/23/2023]
Abstract
We have studied niobium superconducting thin wires deposited onto a SrTiO3 substrate. By measuring the reflection coefficient of the wires, resonances are observed in the superconducting state in the 130 MHz to 4 GHz range. They are interpreted as standing wave resonances of one-dimensional plasma modes propagating along the superconducting wire. The experimental dispersion law, omega versus q, presents a linear dependence over the entire wave vector range. The modes are softened as the temperature increases close the superconducting transition temperature. Very good agreement is obtained between our data and the predicted dispersion relation of one-dimensional plasma modes.
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Affiliation(s)
- B Camarota
- Centre de Recherches sur les Très Basses Températures, Université Joseph Fourier, CNRS, Grenoble, France
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Mayfrank L, Kim Y, Kissler J, Delsing P, Gilsbach JM, Schröder JM, Weis J. Morphological changes following experimental intraventricular haemorrhage and intraventricular fibrinolytic treatment with recombinant tissue plasminogen activator. Acta Neuropathol 2000; 100:561-7. [PMID: 11045679 DOI: 10.1007/s004010000219] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Intraventricular haemorrhage (IVH) occurs in up to 50% of patients with primary intracerebral haemorrhage and aneurysmal subarachnoid haemorrhage. It is a significant and independent contributor to mortality and morbidity in these intracranial haemorrhages. Using a model of isolated IVH, we assessed the morphological changes induced by intraventricular bleeding and investigated the effects of intraventricular fibrinolytic treatment following IVH. IVH was induced in 32 pigs by intraventricular infusion of 10 ml autologous blood along with thrombin. The treatment group received an intraventricular injection of 1.5 mg (1 mg/ml) tissue plasminogen activator (tPA) following the injection of blood. The placebo group received the same volume of normal saline. Morphological examinations of the brains were carried out 7 days and 6 weeks following IVH. The ventricles were incompletely filled with blood and significantly enlarged in the placebo group 7 days after the IVH. In contrast, no residual intraventricular clots were visible in the animals treated with tPA, and the diameters of the lateral ventricles had returned to normal within 7 days. Marked losses of the ependymal covering of the ventricular walls were found in the placebo-treated animals, while the ependymal layer was largely intact in the animals treated with tPA. No haemorrhages induced by tPA were observed. The results indicate that intraventricularly administered tPA significantly enhances the lysis of intraventricular blood clots, accelerates the resolution of acute posthaemorrhagic hydrocephalus, and preserves the integrity of the ependymal layer.
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Affiliation(s)
- L Mayfrank
- Neurochirurgische Klinik, Universitätsklinikum der RWTH Aachen, Germany.
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Shimada H, Delsing P. Current mirror effect and correlated cooper-pair transport in coupled arrays of small Josephson junctions. Phys Rev Lett 2000; 85:3253-3256. [PMID: 11019314 DOI: 10.1103/physrevlett.85.3253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/1999] [Indexed: 05/23/2023]
Abstract
We have measured the transport properties of capacitively coupled one-dimensional arrays of small aluminum Josephson junctions. Under suitable biasing conditions, the samples act as current mirrors; the currents in the two arrays couple to each other and become equally large. The coupling is found both for currents flowing in the same direction and in opposite directions. We have also measured the time dependent fluctuations of the currents in the two arrays, and we find a strong correlation or anticorrelation of the fluctuations depending on the relative direction of the two currents.
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Affiliation(s)
- H Shimada
- Microtechnology Center at Chalmers MC2, Department of Microelectronics and Nanoscience, Chalmers University of Technology and Göteborg University, Sweden
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Krasnov VM, Yurgens A, Winkler D, Delsing P, Claeson T. Evidence for coexistence of the superconducting gap and the pseudogap in Bi-2212 from intrinsic tunneling spectroscopy. Phys Rev Lett 2000; 84:5860-5863. [PMID: 10991073 DOI: 10.1103/physrevlett.84.5860] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2000] [Indexed: 05/23/2023]
Abstract
We present intrinsic tunneling spectroscopy measurements on small Bi2Sr2CaCu2O8+x mesas. The tunnel conductance curves show both sharp peaks at the superconducting gap voltage and broad humps representing the c-axis pseudogap. The superconducting gap vanishes at Tc, while the pseudogap exists both above and below Tc. Our observation implies that the superconducting and pseudogaps represent different coexisting phenomena.
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Affiliation(s)
- V M Krasnov
- Department of Microelectronics and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
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Starmark B, Delsing P, Haviland D, Claeson T. Noise measurements of single electron transistors using a transimpedance amplifier. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0964-1807(99)00051-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Schoelkopf RJ, Wahlgren P, Kozhevnikov AA, Delsing P, Prober DE. The radio-frequency single-electron transistor (RF-SET): A fast and ultrasensitive electrometer. Science 1998; 280:1238-42. [PMID: 9596572 DOI: 10.1126/science.280.5367.1238] [Citation(s) in RCA: 598] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A new type of electrometer is described that uses a single-electron transistor (SET) and that allows large operating speeds and extremely high charge sensitivity. The SET readout was accomplished by measuring the damping of a 1.7-gigahertz resonant circuit in which the device is embedded, and in some ways is the electrostatic "dual" of the well-known radio-frequency superconducting quantum interference device. The device is more than two orders of magnitude faster than previous single-electron devices, with a constant gain from dc to greater than 100 megahertz. For a still-unoptimized device, a charge sensitivity of 1.2 x 10(-5) e/hertz was obtained at a frequency of 1.1 megahertz, which is about an order of magnitude better than a typical, 1/f-noise-limited SET, and corresponds to an energy sensitivity (in joules per hertz) of about 41 Planck's over 2pi.
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Affiliation(s)
- RJ Schoelkopf
- R. J. Schoelkopf, A. A. Kozhevnikov, D. E. Prober, Departments of Applied Physics and Physics, Yale University, New Haven, CT 06520-8284, USA. P. Wahlgren and P. Delsing, Department of Microelectronics and Nanoscience, Chalmers Uni
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Mayfrank L, Kissler J, Raoofi R, Delsing P, Weis J, Küker W, Gilsbach JM. Ventricular dilatation in experimental intraventricular hemorrhage in pigs. Characterization of cerebrospinal fluid dynamics and the effects of fibrinolytic treatment. Stroke 1997; 28:141-8. [PMID: 8996503 DOI: 10.1161/01.str.28.1.141] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND AND PURPOSE Hemorrhagic ventricular dilatation (HVD) is a prominent feature of human intraventricular hemorrhage (IVH) and a strong indicator for poor outcome. We developed an IVH model to define the mechanisms responsible for HVD and to test the efficacy of intraventricular administration of tissue plasminogen activator (TPA) in the treatment of HVD. METHODS Isolated IVH was produced in pigs by injecting 10 mL of blood simultaneously with thrombin into the right lateral ventricle. The treatment group received 1.5 mg of TPA after induction of IVH. Intraventricular blood volume and the volume of the lateral ventricles were assessed by CT after 90 minutes, 7 days, and 42 days. Intracranial pressure, the pressure-volume index, and the resistance to outflow of cerebrospinal fluid (R(out)) were measured 30 minutes and 7 days after IVH. RESULTS After IVH, the volume of the lateral ventricles increased from 1.98 +/- 0.69 to 6.43 +/- 1.23 mL (P < .001). There was a linear relationship between ventricular and clot volume (P = .014). Initially, R(out) increased from 24.34 +/- 7.13 to 63.56 +/- 64.91 mm Hg/mL per minute (P < .001). After 7 days, restoration of normal cerebrospinal fluid circulation occurred, but the ventricles were still significantly enlarged (5.24 +/- 1.76 mL, P < .001) and filled with blood. Within 6 weeks, ventricular volume had returned to normal values, paralleled by complete clot resolution. Intraventricular administration of TPA significantly accelerated clot clearance and restoration of normal ventricle volume. CONCLUSIONS These results suggest that intraventricular bleeding may cause impairment of cerebrospinal fluid circulation but that the mass effect of clots distending the ventricle walls is the most important mechanism responsible for HVD. This model closely imitates several prominent features of human IVH and may therefore be a useful tool for preclinical assessment of the efficacy and safety of treatment with TPA.
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Affiliation(s)
- L Mayfrank
- Department of Neurosurgery, Medical Faculty of the University of Technology (RWTH), Aachen, Germany
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Chen CD, Delsing P, Haviland DB, Harada Y, Claeson T. Flux flow and vortex tunneling in two-dimensional arrays of small Josephson junctions. Phys Rev B Condens Matter 1996; 54:9449-9457. [PMID: 9984683 DOI: 10.1103/physrevb.54.9449] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Haviland DB, Delsing P. Cooper-pair charge solitons: The electrodynamics of localized charge in a superconductor. Phys Rev B Condens Matter 1996; 54:R6857-R6860. [PMID: 9984398 DOI: 10.1103/physrevb.54.r6857] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Pettersson J, Wahlgren P, Delsing P, Haviland DB, Claeson T, Rorsman N, Zirath H. Extending the high-frequency limit of a single-electron transistor by on-chip impedance transformation. Phys Rev B Condens Matter 1996; 53:R13272-R13274. [PMID: 9983165 DOI: 10.1103/physrevb.53.r13272] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Wahlgren P, Delsing P, Haviland DB. Crossover from global to local rule for the Coulomb blockade in small tunnel junctions. Phys Rev B Condens Matter 1995; 52:R2293-R2296. [PMID: 9981394 DOI: 10.1103/physrevb.52.r2293] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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50
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Petrashov VT, Antonov VN, Delsing P, Claeson T. Phase controlled conductance of mesoscopic structures with superconducting "mirrors". Phys Rev Lett 1995; 74:5268-5271. [PMID: 10058725 DOI: 10.1103/physrevlett.74.5268] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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