| 1. |
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| 2. |
- Batista, P.D., et al.
(författare)
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Acousto-electric single-photon detector
- 2007
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 6583, s. 658304-
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel concept for a semiconductor-based single-photon detector for quantum information processing, which is capable of discriminating the number of photons in a light pulse. The detector exploits the charge transport by a surface acoustic wave (SAW) in order to combine a large photon absorption area (thus providing high photon collection efficiency) with a microscopic charge detection area, where the photo generated charge is detected with resolution at the single electron level using single electron transistors (SETs). We present preliminary results on acoustic transport measured in a prototype for the detector as well as on the fabrication of radio-frequency single-electron transistors (RFSETs) for charge detection. The photon detector is a particular example of acousto-electric nanocircuits that are expected to be able to control both the spatial and the spin degrees of freedom of single electrons. If realized, these circuits will contribute substantially to a scalable quantum information technology.
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| 3. |
- Roschier, L, et al.
(författare)
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Noise performance of the radio-frequency single-electron transistor
- 2004
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 95:3, s. 1274-1286
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Tidskriftsartikel (refereegranskat)abstract
- Measurements were performed on aluminum and multiwalled carbon nanotube radio-frequency single-electron transistors (RF-SETs) and analyzed the results carefully. A detailed noise model based on scattering matrix and noise wave formalisms was developed. The signal-to-noise ratios obtained from the model agree well with the measured charge sensitivities. It was found that, in the setup, the first stage HEMT amplifier was the most inadequate component contributing nearly all of the charge noise.
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| 4. |
- Andersson, K., et al.
(författare)
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Synchronous Cooper pair tunneling in a 1D-array of Josephson junctions
- 2000
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 284, s. 1816-1817
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Tidskriftsartikel (refereegranskat)abstract
- We have studied 1D-arrays of Josephson junctions with a gate capacitively coupled to the middle of the array. The SQUID shape of each junction enables tuning of the Josephson coupling energy, El. By adding a signal to the gate with a radio-frequency f we create a step in the I-V characteristics at the value I = 2ef: The step is clearly visible as a peak in the differential resistance dI/dV and can be seen in the whole frequency range studied (10-90 MHz).
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| 5. |
- Bergsten, T., et al.
(författare)
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Hall resistance in two-dimensional arrays of Josephson junctions
- 2000
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 284, s. 1818-1819
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the Hall resistance in two-dimensional arrays of ultrasmall aluminium Josephson junctions. We found that the Hall resistance was periodical with respect to an external magnetic field applied perpendicular to the plane of the array. We also found that the Hall resistance was affected by an applied voltage to a nearby gate electrode, but not by a gate plane silting underneath the array.
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| 6. |
- Bruschi, D. E., et al.
(författare)
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Towards universal quantum computation through relativistic motion
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)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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| 7. |
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| 8. |
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| 9. |
- Delsing, Jerker, et al.
(författare)
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Sources and propagation of eectromagnetic transients in railway systems, S01-3915/08. Final Report
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The railway system is continuously being updated. Upgrading axle loads, introducing new engines with increasing power needs and advanced motor control give unwanted electromagnetic consequences for electronic-, telecommunication-, and signalling systems along the track. This can, for example, lead to failure in detector systems and traffic control systems and increased cost due to corrective maintenance. This research project was initiated with the purpose of understanding origin and propagation of radiated and conducted electromagnetic transients in the railway system. To investigate the problem of radiated and conducted electromagnetic interference, it has been necessary to develop new measuring methods. Measurements have been conducted to determine if the more sensitive low voltage systems are influenced by higher voltage systems. An existing electromagnetic modeling tool has been utilized, to model crosstalk between the rails and the overhead line catenary system, and modified to incorporate a combination of two- and three- dimensional models to reduce time and space complexity. The resulting simulation environment can be used to analyze possible sources of electromagnetic disturbances in the coexisting signaling circuitry of today, and to reduce the influence of these sources. This gives a new application of the measurement method and further development of a simulation tool. One of the objectives in this project has been to find out the tolerance of the low voltage detector systems in presence of the higher voltage system used in the railways. One of the conclusions is that correct installation is important and that failure to comply with installation procedures results in high electromagnetic interference. There is no correlation between the presence of trains and randomly occurring disturbances.
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| 10. |
- Delsing, Per, 1959, et al.
(författare)
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The 2019 surface acoustic waves roadmap
- 2019
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 52:35
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Forskningsöversikt (refereegranskat)abstract
- Today, surface acoustic waves (SAWs) and bulk acoustic waves are already two of the very few phononic technologies of industrial relevance and can been found in a myriad of devices employing these nanoscale earthquakes on a chip. Acoustic radio frequency filters, for instance, are integral parts of wireless devices. SAWs in particular find applications in life sciences and microfluidics for sensing and mixing of tiny amounts of liquids. In addition to this continuously growing number of applications, SAWs are ideally suited to probe and control elementary excitations in condensed matter at the limit of single quantum excitations. Even collective excitations, classical or quantum are nowadays coherently interfaced by SAWs. This wide, highly diverse, interdisciplinary and continuously expanding spectrum literally unites advanced sensing and manipulation applications. Remarkably, SAW technology is inherently multiscale and spans from single atomic or nanoscopic units up even to the millimeter scale. The aim of this Roadmap is to present a snapshot of the present state of surface acoustic wave science and technology in 2019 and provide an opinion on the challenges and opportunities that the future holds from a group of renown experts, covering the interdisciplinary key areas, ranging from fundamental quantum effects to practical applications of acoustic devices in life science.
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| 11. |
- Echternach, P. M., et al.
(författare)
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Progress in the development of a single Cooper-pair box qubit
- 2009
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Ingår i: Quantum Information Processing. - : Springer Science and Business Media LLC. - 1570-0755 .- 1573-1332. ; 8:2-3, s. 183-198
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Tidskriftsartikel (refereegranskat)abstract
- We describe in this review progress in techniques for measuring the quantum states of the single Cooper-pair box (SCB) at the Jet Propulsion Laboratory, and the use of these techniques to characterize their performance as quantum bits. Initially, the Radio-Frequency-Single-Electron Transistor was used to measure conventional and differential versions of the SCB. To overcome some of the difficulties associated with the radio-frequency single-electron transistor, a transition was made to readout based on the quantum capacitance technique. Using this method, entanglement between two SCBs was demonstrated spectroscopically and with ground state characterization.
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| 12. |
- Gustafsson, Martin, 1979, et al.
(författare)
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Local probing of propagating acoustic waves in a gigahertz echo chamber
- 2012
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2481 .- 1745-2473. ; 8:4, s. 338-343
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Tidskriftsartikel (refereegranskat)abstract
- In the same way that micro-mechanical resonators resemble guitar strings and drums, surface acoustic waves resemble the sound these instruments produce, but moving over a solid surface rather than through air. In contrast with oscillations in suspended resonators, such propagating mechanical waves have not before been studied near the quantum mechanical limits. Here, we demonstrate local probing of surface acoustic waves with a displacement sensitivity of 30 amRMS Hz^(−1/2) and detection sensitivity on the single-phonon level after averaging, at a frequency of 932 MHz. Our probe is a piezoelectrically coupled single-electron transistor, which is sufficiently fast, non-destructive and localized to enable us to track pulses echoing back and forth in a long acoustic cavity, self-interfering and ringing the cavity up and down. We project that strong coupling to quantum circuits will enable new experiments, and hybrids using the unique features of surface acoustic waves. Prospects include quantum investigations of phonon–phonon interactions, and acoustic coupling to superconducting qubits for which we present favourable estimates.
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| 13. |
- Haviland, David B., et al.
(författare)
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Quantum-phase transition in 1D Josephson junction arrays
- 2000
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 284, s. 1808-1809
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Tidskriftsartikel (refereegranskat)abstract
- One-dimensional arrays of small capacitance SQUIDs have been studied experimentally. The effective Josephson coupling between neighboring electrodes is tunable in situ. The arrays can be tuned from a Josephson-like state, with low resistance and sharp critical current, to a Coulomb blockade state, with infinite resistance and sharp threshold voltage. A quantum phase transition occurs at the crossover between these two types of behavior, which is evident from an analysis of the temperature dependence of the zero bias resistance.
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| 14. |
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| 15. |
- Krasnov, Vladimir M., et al.
(författare)
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Anticorrelation between temperature and fluctuations of the switching current in moderately damped Josephson junctions
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 76:22, s. 224517-
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Tidskriftsartikel (refereegranskat)abstract
- Presented are the results of calculations suggesting that the quasi-one-dimensional organic superconductors (TMTSF)2X (where TMTSF represents tetramethyltetraselenafulvalene and X is PF6 AsF6, ClO4, etc.) may show a substantial increase in their superconducting and spin-density-wave ordering temperatures when the Fermi level is raised through application of an electrostatic gating voltage. A rich behavior is observed, strongly dependent on the form of the superconducting order parameter, as the Fermi level approaches the Van Hove singularity at ka=0. Included are predictions for the behavior of these materials under zero and moderate applied pressure. It is found that TSDW as high as 50 K and superconducting Tc as high as 20 K may be achieved at optimal gate voltages of approximately 100 mV.
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| 16. |
- Lin, Wei Ju, et al.
(författare)
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Deterministic Loading of Microwaves onto an Artificial Atom Using a Time-Reversed Waveform
- 2022
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 22:20, s. 8137-8142
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Tidskriftsartikel (refereegranskat)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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| 17. |
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| 18. |
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| 19. |
- Shaw, M. D., et al.
(författare)
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Characterization of an entangled system of two superconducting qubits using a multiplexed capacitance measurement
- 2009
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 79:1
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Tidskriftsartikel (refereegranskat)abstract
- We characterize a pair of Cooper-pair boxes coupled with a fixed capacitor using spectroscopy and measurements of the ground-state quantum capacitance. We use the extracted parameters to estimate the concurrence or degree of entanglement between the two qubits. We also present a thorough demonstration of a multiplexed quantum capacitance measurement technique, which is in principle scalable to a large array of superconducting qubits.
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| 20. |
- Shaw, M. D., et al.
(författare)
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Experimental realization of a differential charge qubit
- 2007
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 17:2, s. 109-112
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the operation of a differential single Cooper-pair box, a charge qubit consisting of two aluminum islands, isolated from ground, coupled by a pair of small-area Josephson junctions. We have tested four devices, all of which show evidence of quasiparticle poisoning. The devices are characterized with microwave spectroscopy and temperature dependence studies. © 2007 IEEE.
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| 21. |
- Shaw, M. D., et al.
(författare)
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Kinetics of nonequilibrium quasiparticle tunneling in superconducting charge qubits
- 2008
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 78:2, s. 024503-
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Tidskriftsartikel (refereegranskat)abstract
- We directly observe low-temperature nonequilibrium quasiparticle tunneling in charge qubits based on the single-Cooper-pair box. We measure even- and odd-state dwell-time distributions as a function of temperature, and interpret these results using a kinetic theory. While the even-state lifetime is exponentially distributed, the odd-state distribution is more heavily weighted to short times, implying that odd-to-even tunnel events are not described by a homogenous Poisson process. The mean odd-state dwell time increases sharply at low temperature, which is consistent with quasiparticles tunneling out of the island before reaching thermal equilibrium.
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| 22. |
- Staudt, Matthias, 1977, et al.
(författare)
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Coupling of an erbium spin ensemble to a superconducting resonator
- 2012
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 1361-6455 .- 0953-4075. ; 45:12, s. Art. no. 124019-
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Tidskriftsartikel (refereegranskat)abstract
- A quantum coherent interface between optical and microwave photons can be used as a basic building block within a future quantum information network. The interface is envisioned as an ensemble of rare-earth ions coupled to a superconducting resonator, allowing for coherent transfer between optical and microwave photons. Towards this end, we have realized a hybrid device coupling a Er3+-doped Y2SiO5 crystal in a superconducting coplanar waveguide cavity. We observe a collective spin coupling of 4 MHz and a spin linewidth of down to 75 MHz.
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| 23. |
- Wen, P. Y., et al.
(författare)
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Large Collective Lamb Shift of Two Distant Superconducting Artificial Atoms
- 2019
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 122:23
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Tidskriftsartikel (refereegranskat)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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| 24. |
- Wiegand, Emely, 1988, et al.
(författare)
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Ultimate quantum limit for amplification: A single atom in front of a mirror
- 2021
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:4
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Tidskriftsartikel (refereegranskat)abstract
- We investigate three types of amplification processes for light fields coupling to an atom near the end of a one-dimensional (1D) semi-infinite waveguide. We consider two setups where a drive creates population inversion in the bare or dressed basis of a three-level atom and one setup where the amplification is due to higher-order processes in a driven two-level atom. In all cases, the end of the waveguide acts as a mirror for the light. We find that this enhances the amplification in two ways compared to the same setups in an open waveguide. Firstly, the mirror forces all output from the atom to travel in one direction instead of being split up into two output channels. Secondly, interference due to the mirror enables tuning of the ratio of relaxation rates for different transitions in the atom to increase population inversion. We quantify the enhancement in amplification due to these factors and show that it can be demonstrated for standard parameters in experiments with superconducting quantum circuits.
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| 25. |
- Zlatev, Jordan, et al.
(författare)
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The acquisition of motion event constructions in Thai.
- 2003
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Ingår i: Grammatik i fokus : festskrift till Christer Platzack den 18 november 2003 = Grammar in focus : festschrift for Christer Platzack 18 November 2003. Vol. II. - 9163145715
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
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