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Pris, A. D., Utturkar, Y., Surman, C., Morris, W. G., Vert, A., Zalyubovskiy, S., et al. (2012). Towards high-speed imaging of infrared photons with bio-inspired nanoarchitectures. Nat. Photon., 6(3), 195–200.
Abstract: Existing infrared detectors rely on complex microfabrication and thermal management methods. Here, we report an attractive platform of low-thermal-mass resonators inspired by the architectures of iridescent Morpho butterfly scales. In these resonators, the optical cavity is modulated by its thermal expansion and refractive index change, resulting in `wavelength conversion' of mid-wave infrared (3-8 µm) radiation into visible iridescence changes. By doping Morpho butterfly scales with single-walled carbon nanotubes, we achieved mid-wave infrared detection with 18-62 mK noise-equivalent temperature difference and 35-40 Hz heat-sink-free response speed. The nanoscale pitch and the extremely small thermal mass of individual `pixels' promise significant improvements over existing detectors. Computational analysis explains the origin of this thermal response and guides future conceptually new bio-inspired thermal imaging sensor designs.
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Ulhaq, A., Weiler, S., Ulrich, S. M., Roßbach, R., Jetter, M., & Michler, P. (2012). Cascaded single-photon emission from the Mollow triplet sidebands of a quantum dot. Nat. Photon., 6(4), 238–242.
Abstract: Emission from a resonantly excited quantum emitter is a fascinating research topic within the field of quantum optics and is a useful source for different types of quantum light fields. The resonance spectrum consists of a single spectral line that develops into a triplet above saturation of the quantum emitter. The three closely spaced photon channels from the resonance fluorescence have different photon statistical signatures. We present a detailed photon statistics analysis of the resonance fluorescence emission triplet from a solid-state-based artificial atom, that is, a semiconductor quantum dot. The photon correlation measurements demonstrate both `single' and `cascaded' photon emission from the Mollow triplet sidebands. The bright and narrow sideband emission (5.9 × 106 photons per second into the first lens) can be conveniently frequency-tuned by laser detuning over 15 times its linewidth (Δv ~ 1.0 GHz). These unique properties make the Mollow triplet sideband emission a valuable light source for quantum light spectroscopy and quantum information applications, for example.
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Kim, Y. - S., Lee, J. - C., Kwon, O., & Kim, Y. - H. (2012). Protecting entanglement from decoherence using weak measurement and quantum measurement reversal. Nat. Phys., 8(2), 117–120.
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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Pütz, P., Honingh, C. E., Jacobs, K., Justen, M., Schultz, M., & Stutzki, J. (2012). Terahertz hot electron bolometer waveguide mixers for GREAT. A&A, 542, L2.
Abstract: Context. Supplementing the publications based on the first-light observations with the German REceiver for Astronomy at Terahertz frequencies (GREAT) on SOFIA, we present background information on the underlying heterodyne detector technology. This Letter complements the GREAT instrument Letter and focuses on the mixers itself.
Aims. We describe the superconducting hot electron bolometer (HEB) detectors that are used as frequency mixers in the L1 (1400 GHz), L2 (1900 GHz), and M (2500 GHz) channels of GREAT. Measured performance of the detectors is presented and background information on their operation in GREAT is given.
Methods. Our mixer units are waveguide-based and couple to free-space radiation via a feedhorn antenna. The HEB mixers are designed, fabricated, characterized, and flight-qualified in-house. We are able to use the full intermediate frequency bandwidth of the mixers using silicon-germanium multi-octave cryogenic low-noise amplifiers with very low input return loss.
Results. Superconducting HEB mixers have proven to be practical and sensitive detectors for high-resolution THz frequency spectroscopy on SOFIA. We show that our niobium-titanium-nitride (NbTiN) material HEBs on silicon nitride (SiN) membrane substrates have an intermediate frequency (IF) noise roll-off frequency above 2.8 GHz, which does not limit the current receiver IF bandwidth. Our mixer technology development efforts culminate in the first successful operation of a waveguide-based HEB mixer at 2.5 THz and deployment for radioastronomy. A significant contribution to the success of GREAT is made by technological development, thorough characterization and performance optimization of the mixer and its IF interface for receiver operation on SOFIA. In particular, the development of an optimized mixer IF interface contributes to the low passband ripple and excellent stability, which GREAT demonstrated during its initial successful astronomical observation runs.
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Mineev, V. P. (2012). Superfluid helium: Order in disorder. Nat. Phys., 8, 253–254.
Abstract: Confining liquid 3He in porous silica aerogel prepared with strong anisotropy stabilizes a state of axial superfluidity.
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Steudle, G. A., Schietinger, S., Höckel, D., Dorenbos, S. N., Zadeh, I. E., Zwiller, V., et al. (2012). Measuring the quantum nature of light with a single source and a single detector. Phys. Rev. A, 86(5), 053814.
Abstract: An elementary experiment in optics consists of a light source and a detector. Yet, if the source generates nonclassical correlations such an experiment is capable of unambiguously demonstrating the quantum nature of light. We realized such an experiment with a defect center in diamond and a superconducting detector. Previous experiments relied on more complex setups, such as the Hanbury Brown and Twiss configuration, where a beam splitter directs light to two photodetectors, creating the false impression that the beam splitter is a fundamentally required element. As an additional benefit, our results provide a simplification of the widely used photon-correlation techniques.
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Akalin, T. (2012). Terahertz sources: Powerful photomixers. Nat. Photon., 6(2), 81.
Abstract: An efficient continuous-wave source of terahertz radiation that combines the outputs from two near-infrared semiconductor lasers in a novel photomixer looks set to benefit applications in spectroscopy and imaging.
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Inderbitzin, K., Engel, A., Schilling, A., Il'in, K., & Siegel, M. (2012). An ultra-fast superconducting Nb nanowire single-photon detector for soft x-rays. Appl. Phys. Lett., 101.
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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Bason, M. G., Viteau, M., Malossi, N., Huillery, P., Arimondo, E., Ciampini, D., et al. (2012). High-fidelity quantum driving. Nat. Phys., 8(2), 147–152.
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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Казаков, А. Ю., Кардакова, А. И., Селиверстов, С. В., Горшков, К. Н., Дивочий, А. В., Финкель, М. И., et al. (2012). Возможность применения сверхпроводниковых материалов в качестве отражающего покрытия холодного зеркала телескопа субмиллиметрового диапазона. Совр. проб. науки и обр., (3), 1–5.
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