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| Author | Hase, Muneaki; Katsuragawa, Masayuki; Constantinescu, Anca Monia; Petek, Hrvoje | ||||
| Title | Frequency comb generation at terahertz frequencies by coherent phonon excitation in silicon | Type  |
Journal Article | ||
| Year | 2012 | Publication | Nature Photonics | Abbreviated Journal | Nat. Photon. |
| Volume | 6 | Issue | Pages | 243–247 | |
| Keywords | fromIPMRAS | ||||
| Abstract | High-order nonlinear light–matter interactions in gases enable the generation of X-ray and attosecond light pulses, metrology and spectroscopy1. Optical nonlinearities in solid-state materials are particularly interesting for combining optical and electronic functions for high-bandwidth information processing2. Third-order nonlinear optical processes in silicon have been used to process optical signals with bandwidths greater than 1 GHz (ref. 2). However, fundamental physical processes for a silicon-based optical modulator in the terahertz bandwidth range have not yet been explored. Here, we demonstrate ultrafast phononic modulation of the optical index of silicon by irradiation with intense few-cycle femtosecond pulses. The anisotropic reflectivity modulation by the resonant Raman susceptibility at the fundamental frequency of the longitudinal optical phonon of silicon (15.6 THz) generates a frequency comb up to seventh order. All-optical >100 THz frequency comb generation is realized by harnessing the coherent atomic motion of the silicon crystalline lattice at its highest mechanical frequency. | ||||
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| Notes | Approved | no | |||
| Call Number | RPLAB @ gujma @ | Serial | 794 | ||
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| Author | Mineev, Vladimir P. | ||||
| Title | Superfluid helium: Order in disorder | Type |
Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | Pages | 253–254 | |
| Keywords | fromIPMRAS | ||||
| Abstract | Confining liquid 3He in porous silica aerogel prepared with strong anisotropy stabilizes a state of axial superfluidity. | ||||
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| Notes | Approved | no | |||
| Call Number | RPLAB @ gujma @ | Serial | 810 | ||
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| Author | Clerk, Aashish | ||||
| Title | Quantum phononics: To see a SAW | Type |
Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | 4 | Pages | 256-257 |
| Keywords | fromIPMRAS | ||||
| Abstract | Mechanical oscillations of microscopic resonators have recently been observed in the quantum regime. This idea could soon be extended from localized vibrations to travelling waves thanks to a sensitive probe of so-called surface acoustic waves. | ||||
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| Notes | Approved | no | |||
| Call Number | RPLAB @ gujma @ | Serial | 811 | ||
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| Author | Hollenberg, Lloyd C. L. | ||||
| Title | Quantum control: Through the quantum chicane | Type |
Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | 2 | Pages | 113-114 |
| Keywords | fromIPMRAS | ||||
| Abstract | In quantum control there is an inherent tension between high fidelity requirements and the need for speed to avoid decoherence. A direct comparison of quantum control protocols at these two extremes indicates where the sweet spot may lie. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 812 | ||
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| Author | Gustafsson, Martin V.; Santos, Paulo V.; Johansson, Göran; Delsing, Per | ||||
| Title | Local probing of propagating acoustic waves in a gigahertz echo chamber | Type |
Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | 4 | Pages | 338-343 |
| Keywords | fromIPMRAS | ||||
| 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 30amRMSHz-1/2 and detection sensitivity on the single-phonon level after averaging, at a frequency of 932MHz. 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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| Notes | Approved | no | |||
| Call Number | RPLAB @ gujma @ | Serial | 813 | ||
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| Author | Korotkov, Alexander N. | ||||
| Title | Entanglement preservation: The Sleeping Beauty approach | Type |
Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | 2 | Pages | 107-108 |
| Keywords | fromIPMRAS | ||||
| Abstract | Two-qubit entanglement can be preserved by partially measuring the qubits to leave them in a 'lethargic' state. The original state is restored using quantum measurement reversal after the qubits have travelled through a decoherence channel. | ||||
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| Notes | Approved | no | |||
| Call Number | RPLAB @ gujma @ | Serial | 814 | ||
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| Author | Kim, Yong-Su; Lee, Jong-Chan; Kwon, Osung; Kim, Yoon-Ho | ||||
| Title | Protecting entanglement from decoherence using weak measurement and quantum measurement reversal | Type |
Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | 2 | Pages | 117-120 |
| Keywords | fromIPMRAS | ||||
| Abstract | Decoherence, often caused by unavoidable coupling with the environment, leads to degradation of quantum coherence. For a multipartite quantum system, decoherence leads to degradation of entanglement and, in certain cases, entanglement sudden death. Tackling decoherence, thus, is a critical issue faced in quantum information, as entanglement is a vital resource for many quantum information applications including quantum computing, quantum cryptography, quantum teleportation and quantum metrology. Here, we propose and demonstrate a scheme to protect entanglement from decoherence. Our entanglement protection scheme makes use of the quantum measurement itself for actively battling against decoherence and it can effectively circumvent even entanglement sudden death. | ||||
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| Notes | Approved | no | |||
| Call Number | RPLAB @ gujma @ | Serial | 815 | ||
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| Author | Bason, Mark G.; Viteau, Matthieu; Malossi, Nicola; Huillery, Paul; Arimondo, Ennio; Ciampini, Donatella; Fazio, Rosario; Giovannetti, Vittorio; Mannella, Riccardo; Morsch, Oliver | ||||
| Title | High-fidelity quantum driving | Type |
Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | 2 | Pages | 147-152 |
| Keywords | fromIPMRAS | ||||
| Abstract | Accurately controlling a quantum system is a fundamental requirement in quantum information processing and the coherent manipulation of molecular systems. The ultimate goal in quantum control is to prepare a desired state with the highest fidelity allowed by the available resources and the experimental constraints. Here we experimentally implement two optimal high-fidelity control protocols using a two-level quantum system comprising Bose-Einstein condensates in optical lattices. The first is a short-cut protocol that reaches the maximum quantum-transformation speed compatible with the Heisenberg uncertainty principle. In the opposite limit, we realize the recently proposed transitionless superadiabatic protocols in which the system follows the instantaneous adiabatic ground state nearly perfectly. We demonstrate that superadiabatic protocols are extremely robust against control parameter variations, making them useful for practical applications. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 816 | ||
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| Author | Henrich, D.; Dorner,S.; Hofherr, M.; Il'in, K.; Semenov, A.; Heintze, E.; Scheffler, M.; Dressel, M.; Siegel, M. | ||||
| Title | Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content | Type |
Journal Article | ||
| Year | 2012 | Publication | Abbreviated Journal | J. Appl. Phys. | |
| Volume | 112 | Issue | Pages | ||
| Keywords | SSPD, SNSPD, magnetron sputtering, spectrum, NbN film, nitrogen concentration | ||||
| Abstract | The spectral detection efficiency and the dark count rate of superconducting nanowire single-photon detectors (SNSPD) have been studied systematically on detectors made from thin NbN films with different chemical compositions. Reduction of the nitrogen content in the 4 nm thick NbN films results in a decrease of the dark count rates more than two orders of magnitude and in a red shift of the cut-off wavelength of the hot-spot SNSPD response. The observed phenomena are explained by an improvement of uniformity of NbN films that has been confirmed by a decrease of resistivity and an increase of the ratio of the measured critical current to the depairing current. The latter factor is considered as the most crucial for both the cut-off wavelength and the dark count rates of SNSPD. Based on our results we propose a set of criteria for material properties to optimize SNSPD in the infrared spectral region. VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4757625] |
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| Corporate Author | D. Henrich, S. Dorner, M. Hofherr, K. Il'in, A. Semenov, E. Heintze, M. Scheffler, M. Dressel, M. Siegel | Thesis | |||
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| Language | English | Summary Language | Original Title | Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content | |
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| Call Number | RPLAB @ seleznev @ | Serial | 877 | ||
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| Author | Inderbitzin, K.; Engel, A.; Schilling, A.; Il'in, K.; Siegel, M. | ||||
| Title | An ultra-fast superconducting Nb nanowire single-photon detector for soft x-rays | Type |
Journal Article | ||
| Year | 2012 | Publication | Abbreviated Journal | Appl. Phys. Lett. | |
| Volume | 101 | Issue | Pages | ||
| Keywords | SSPD, SNSPD, x-ray, Nb | ||||
| Abstract | Although superconducting nanowire single-photon detectors (SNSPDs) are well studied regarding the detection of infrared/optical photons and keV-molecules, no studies on continuous x-ray photon counting by thick-film detectors have been reported so far. We fabricated a 100 nm thick niobium x-ray SNSPD (an X-SNSPD) and studied its detection capability of photons with keV-energies in continuous mode. The detector is capable to detect photons even at reduced bias currents of 0.4%, which is in sharp contrast to optical thin-film SNSPDs. No dark counts were recorded in extended measurement periods. Strikingly, the signal amplitude distribution depends significantly on the photon energy spectrum.VC |
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| Notes | Approved | no | |||
| Call Number | RPLAB @ seleznev @ | Serial | 878 | ||
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