Table of contents



For a brighter tomorrow p501


Photonics societies in the USA join forces in the National Photonics Initiative to increase photonics research and development, grow the USA economy and improve national security.


Books and Arts

New titles at a glance p503

Bionanophotonics: An Introductory Textbook by Shuichi Kinoshita



News and Views

Fibre communications: Time-reversed twin pp507 - 508

Ezra Ip & Joseph M. Kahn


Co-propagating a signal with its phase conjugate along an optical fibre link makes it possible to mitigate unwanted nonlinear distortions and improve the signal-to-noise ratio in long-haul optical communication systems.

See also: Article by Liu et al.

Raman spectroscopy: The effect of field gradient on SERS pp508 - 510

Christine M. Aikens, Lindsey R. Madison & George C. Schatz


Surface-enhanced Raman spectroscopy is normally associated with the enhanced electric fields that arise near metal nanoparticle surfaces. The contribution of field gradients has been unclear, but new research provides insights into their effect.

See also: Letter by Takase et al.

Quantum optics: Spins charge ahead pp510 - 511

Abram L. Falk & David D. Awschalom


The spin of the nitrogen–vacancy centre in diamond is a powerful resource for quantum control. However, control over its charge state lags far behind. Appropriating electrical gating techniques used in quantum-dot devices could bridge this gap.

Plasmonics: Graphene shrinks light p511

David Pile


Quantum information processing: Two become one pp512 - 513

Jonas Schou Neergaard-Nielsen


Scientists experimentally demonstrate a scheme that allows the number of qubits encoded per photon to be varied while keeping the overall quantum information constant. They also propose the inverse 'splitting' process.

See also: Letter by Vitelli et al.

Quantum computation: Boson sampling on a chip pp514 - 515

T. C. Ralph


Small-scale quantum computers made from an array of interconnected waveguides on a glass chip can now perform a task that is considered hard to undertake on a large scale by classical means.

See also: Letter by Tillmann et al. | Letter by Crespi et al.

View from... CLEO Europe 2013: Science over fibre pp515 - 516

Oliver Graydon


The web of optical fibre networks deployed across Europe is proving useful for experiments in optical metrology and sensing in addition to their primary use of carrying Internet data and telephone calls.



Certified quantum non-demolition measurement of a macroscopic material system pp517 - 520

R. J. Sewell, M. Napolitano, N. Behbood, G. Colangelo & M. W. Mitchell


The first true quantum non-demolition measurement of atomic spins by paramagnetic Faraday rotation in a quantum atom–light interface is described. By using an ensemble of 87Rb atoms, quantum state preparation and information–damage trade-off are observed beyond their classical limits by 7 and 12 standard deviations, respectively.

Subject term: Quantum optics

Joining the quantum state of two photons into one pp521 - 526

Chiara Vitelli, Nicolò Spagnolo, Lorenzo Aparo, Fabio Sciarrino, Enrico Santamato & Lorenzo Marrucci


Quantum information circuits for ‘quantum joining’ are proposed, in which two qubits of information encoded in the polarization of two photons are re-encoded into the polarization and path degrees of freedom of a single photon, while keeping the overall quantum information constant. The inverse ‘splitting’ process is also proposed.

Subject term: Quantum optics

See also: News and Views by Neergaard-Nielsen

Towards quantum-dot arrays of entangled photon emitters pp527 - 531

Gediminas Juska, Valeria Dimastrodonato, Lorenzo O. Mereni, Agnieszka Gocalinska & Emanuele Pelucchi


An array of pyramidal site-controlled InGaAs1−δNδ quantum dots is grown on a GaAs substrate to reduce the fine-structure splitting of the intermediate single-exciton energy levels to less than 4 μeV. The quantum dots emit polarization-entangled photons at a maximum fidelity of 0.721 ± 0.043 without external manipulation of the electronic states.

Frequency-agile, rapid scanning spectroscopy pp532 - 534

G.-W. Truong, K. O. Douglass, S. E. Maxwell, R. D. van Zee, D. F. Plusquellic, J. T. Hodges & D. A. Long


Frequency-agile, rapid scanning spectroscopy requires no mechanical motion and provides a scanning rate of 8 kHz per cavity mode at a sensitivity of ~2 × 10-12 cm-1 Hz-1/2, with a scanning range that exceeds 70 GHz. This technique is promising for fast and sensitive trace gas measurements and chemical kinetic studies.

Subject term: Spectroscopy

Wideband dye-sensitized solar cells employing a phosphine-coordinated ruthenium sensitizer pp535 - 539

Takumi Kinoshita, Joanne Ting Dy, Satoshi Uchida, Takaya Kubo & Hiroshi Segawa


Single and tandem dye-sensitized solar cells with high power-conversion efficiencies and large photocurrent densities are fabricated using a photosensitizer whose long wavelength absorption originates from a spin-forbidden single–triplet transition.

Experimental boson sampling pp540 - 544

Max Tillmann, Borivoje Dakić, René Heilmann, Stefan Nolte, Alexander Szameit & Philip Walther


The boson-sampling problem is experimentally solved by implementing Aaronson and Arkhipov's model of computation with photons in integrated optical circuits. These results set a benchmark for a type of quantum computer that can potentially outperform a conventional computer by using only a few photons and linear optical elements.

Subject terms: Fundamental optical physics | Quantum optics

See also: News and Views by Ralph

Integrated multimode interferometers with arbitrary designs for photonic boson sampling pp545 - 549

Andrea Crespi, Roberto Osellame, Roberta Ramponi, Daniel J. Brod, Ernesto F. Galvão, Nicolò Spagnolo, Chiara Vitelli, Enrico Maiorino, Paolo Mataloni & Fabio Sciarrino


The boson-sampling problem was demonstrated by studying three-photon interference in a five-mode integrated interferometer containing three-dimensional S-bent waveguides. Three single photons were input into the interferometer and the probability ratios of all events were measured. The results agree with quantum mechanical predictions for three-photon interference.

See also: News and Views by Ralph

Selection-rule breakdown in plasmon-induced electronic excitation of an isolated single-walled carbon nanotube pp550 - 554

Mai Takase, Hiroshi Ajiki, Yoshihiko Mizumoto, Keiichiro Komeda, Masanobu Nara, Hideki Nabika, Satoshi Yasuda, Hajime Ishihara & Kei Murakoshi


Raman spectroscopy reveals selection-rule breakdown in the transitions of an isolated single-walled carbon nanotube. The breakdown may be caused by metal dimers and the high field gradient in the radial direction of the tubes.

See also: News and Views by Aikens et al.

Towards isolated attosecond pulses at megahertz repetition rates pp555 - 559

Manuel Krebs, Steffen Hädrich, Stefan Demmler, Jan Rothhardt, Amelle Zaïr, Luke Chipperfield, Jens Limpert & Andreas Tünnermann


A fibre-laser-pumped optical parametric amplifier for high-harmonic generation has been used to realize a megahertz-repetition-rate source of extreme-ultraviolet continua, with evidence of isolated attosecond pulses at 0.6 MHz. This technique could potentially enable a vast array of new applications, such as attosecond-resolution coincidence and photoelectron spectroscopy.



Phase-conjugated twin waves for communication beyond the Kerr nonlinearity limit pp560 - 568

Xiang Liu, A. R. Chraplyvy, P. J. Winzer, R. W. Tkach & S. Chandrasekhar


The transmission of a pair of phase-conjugated beams is shown to mitigate nonlinear distortion during optical fibre communication, allowing a 400 Gbit s−1 superchannel to be sent over 12,800 km of optical fibre.

Subject term: Fibre optics and optical communications

See also: News and Views by Ip & Kahn

Few-fJ/bit data transmissions using directly modulated lambda-scale embedded active region photonic-crystal lasers pp569 - 575

Koji Takeda, Tomonari Sato, Akihiko Shinya, Kengo Nozaki, Wataru Kobayashi, Hideaki Taniyama, Masaya Notomi, Koichi Hasebe, Takaaki Kakitsuka & Shinji Matsuo


High-speed modulation and 4.4 fJ bit−1 data transmission is demonstrated using a photonic-crystal nanocavity laser. Its current threshold of 4.8 µA, modulation current efficiency of 2.0 GHz µA−0.5 and output power of 2.17 µW may enable on-chip photonic networks in combination with recently developed high-sensitivity receivers.

Subject terms: Optoelectronic devices and components | Lasers, LEDs and light sources

See also: Interview with Shinji Matsuo



A big leap in energy-saving lasers p576

Interview with Shinji Matsuo


A laser with a record low energy cost has now been demonstrated by using a laser cavity based on photonic crystals. Shinji Matsuo of NTT Photonics Laboratories in Japan talked to Nature Photonics about its significance.