Optics and photonics articles within Nature Physics

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  • Letter |

    Charge carriers in transition metal dichalcogenides have an extra degree of freedom known as valley pseudospin, which is associated with the shape of the energy bands. Experiments show that this pseudospin can be manipulated using magnetic fields.

    • G. Aivazian
    • , Zhirui Gong
    •  & X. Xu

  • Article |

    The relaxation processes of light-emitting excited ions are tunable, but electrical control is challenging. It is now shown that graphene can be used to manipulate the optical emission and relaxation of erbium near-infrared emitters electrically.

    • K. J. Tielrooij
    • , L. Orona
    •  & F. H. L. Koppens

  • News & Views |

    Light emitted near an optical waveguide is captured and equally split into two modes with opposite directions of propagation. By controlling the dipole spin of the emitter, it is possible to break this symmetry and select only one direction.

    • Lorenzo Marrucci

  • News & Views |

    Transferring electrons from the ground state to an excited state by optical pumping usually increases the population of the upper state. But for graphene in an external magnetic field, the pumped state actually gets depleted.

    • Isabella Gierz

  • Article |

    The Jarzynski equality, relating non-equilibrium processes to free-energy differences between equilibrium states, has been verified in a number of classical systems. An ion-trap experiment now succeeds in demonstrating its quantum counterpart.

    • Shuoming An
    • , Jing-Ning Zhang
    •  & Kihwan Kim

  • Article |

    Landau levels in graphene are not equidistant so that transitions between them can be individually probed. Time-resolved optical pumping experiments reveal strong electron–electron scattering resulting in an Auger-depleted zeroth order Landau level.

    • Martin Mittendorff
    • , Florian Wendler
    •  & Stephan Winnerl

  • Article |

    Coupling the fluorescence of cold atoms to plasmons propagating on a gold surface offers a means of controlling the radiation from optical emitters without the need for a cavity.

    • Christian Stehle
    • , Claus Zimmermann
    •  & Sebastian Slama

  • News & Views |

    Plasmons offer the tantalizing prospect of accelerated light–matter interactions. Accelerated dynamics has now been observed in a hybrid plasmonic laser or spaser, capable of producing pulses on ultrafast timescales.

    • Mark Stockman

  • Article |

    Electron scattering limits the optical excitations produced by metal-based lasers to femtosecond timescales. But sub-picosecond pulsing can be achieved in a plasmonic nanowire laser by operating near the surface plasmon frequency.

    • Themistoklis P. H. Sidiropoulos
    • , Robert Röder
    •  & Rupert F. Oulton

  • News & Views |

    Because of near-instant screening, photoexcited electron–hole pairs in metals are hard to investigate experimentally. Femtosecond spectroscopy is now shown to be a viable tool for studying them — and reveals the existence of 'transient excitons'.

    • Thomas Miller

  • Letter |

    Feshbach resonances provide a powerful tool for engineering interactions in ultracold atomic gases. The strong exciton–photon coupling in semiconductor microcavities facilitates the demonstration of a polaritonic Feshbach resonance with promising implications for manipulating polariton quantum fluids.

    • N. Takemura
    • , S. Trebaol
    •  & B. Deveaud

  • Letter |

    Nanoscale metallic tips are a useful source of electrons for material characterization. It is now shown how terahertz radiation can provide precision control and enhancement of photoelectron emission from these sources. The approach can shape the spectrum of the electron pulse, which could pave the way to improvements in ultrafast electron diffraction and transmission electron microscopy.

    • L. Wimmer
    • , G. Herink
    •  & C. Ropers

  • News & Views |

    Without a well-defined cavity, there is no obvious way to control the resonant modes in a random laser. Experiments now show that shaping the optical pump allows for controlled single-mode operation at predetermined lasing wavelengths.

    • Stefan Rotter

  • Letter |

    Random lasers generate the optical feedback required for stimulated emission by scattering light from disordered particles. Their inherent randomness, however, makes controlling the emission wavelength difficult. It is now shown that this problem can be remedied by carefully matching the pump laser to the specific random medium. The concept is applied to a one-dimensional optofluidic device, but could also be applicable to other random lasers.

    • Nicolas Bachelard
    • , Sylvain Gigan
    •  & Patrick Sebbah

  • News & Views |

    An unusual form of symmetry breaking in coupled microresonators with balanced optical gain and loss is now exploited to realize a novel type of optical isolator.

    • Chong Yidong

  • Article |

    It is now shown that coupled optical microcavities bear all the hallmarks of parity–time symmetry; that is, the system’s dynamics are unchanged by both time-reversal and mirror transformations. The resonant nature of microcavities results in unusual effects not seen in previous photonic analogues of parity–time-symmetric systems: for example, light travelling in one direction is resonantly enhanced but there are no resonance peaks going the other way.

    • Bo Peng
    • , Şahin Kaya Özdemir
    •  & Lan Yang

  • News & Views |

    A tiny drum converts between infrared and microwave signals with record efficiency by keeping the beat of both.

    • Mankei Tsang

  • Article |

    An optomechanical system that converts microwaves to optical frequency light and vice versa is demonstrated. The technique achieves a conversion efficiency of approximately 10%. The results indicate that the device could work at the quantum level, up- and down-converting individual photons, if it were cooled to millikelvin temperatures. It could, therefore, form an integral part of quantum-processor networks.

    • R. W. Andrews
    • , R. W. Peterson
    •  & K. W. Lehnert

  • News & Views |

    Defects in the crystal lattice of silicon carbide prove to be a useful room-temperature source of non-classical light.

    • Igor Aharonovich
    •  & Milos Toth

  • Commentary |

    The latest generation of optical atomic clocks has reached such a degree of accuracy that questions about the need to redefine the second are raised. But even without such a redefinition, these breakthroughs will enable unprecedented precision tests of fundamental physics.

    • Helen Margolis

  • News & Views |

    A combination of two Nobel ideas circumvents the trade-off between power and accuracy in ultraviolet spectroscopy.

    • Scott A. Diddams

  • Letter |

    Frequency combs provide a broad series of well-calibrated spectral lines for highly precise metrology and spectroscopy, but this usually involves a trade-off between power and accuracy. A comb created by adjusting the time delay between two optical pulses now enables both. This so-called Ramsey comb could probe fundamental problems such as determining the size of the proton.

    • Jonas Morgenweg
    • , Itan Barmes
    •  & Kjeld S. E. Eikema

  • Article |

    Defects in silicon carbide can produce continuous-wave microwaves at room temperature. Spectroscopic analysis indicates a photoinduced inversion of the population in the spin ground states, which makes the defects a potential route to stimulated amplification of microwave radiation.

    • H. Kraus
    • , V. A. Soltamov
    •  & G. V. Astakhov

  • News & Views |

    Femtosecond pulses from X-ray free-electron lasers offer a powerful method for studying charged collective excitations in materials, and provide a potential route to identifying bosonic quasiparticles in condensed-matter systems.

    • Peter Abbamonte

  • Article |

    A room-temperature motion sensor with record sensitivity is created using a levitating silica nanoparticle. Feedback cooling to reduce the noise arising from Brownian motion enables a detector that is perhaps even sensitive enough to detect non-Newtonian gravity-like forces.

    • Jan Gieseler
    • , Lukas Novotny
    •  & Romain Quidant

  • Letter |

    Femtosecond pulses from X-ray free-electron lasers offer a powerful method for observing the coherent dynamic of phonons in crystalline materials, it is now shown. This time-resolved spectroscopic tool could provide insight into low-energy collective excitations in solids and how they interact at a microscopic level to determine the material’s macroscopic properties.

    • M. Trigo
    • , M. Fuchs
    •  & D. A. Reis

  • News & Views |

    Light pulses with positive and negative effective masses are now generated using optical fibres. Nonlinear interactions between the two can then create self-accelerating pulse pairs, opening a new route to pulse steering.

    • Thomas Philbin

  • Letter |

    An action generates an equal and opposite reaction. If it were possible, however, for one of the two bodies to have negative mass, they would accelerate each other. A situation analogous to this is now realized in an optical system. Solitons moving in an optical mesh lattice exhibit either an effective positive or negative mass, thus enabling observation of self-acceleration.

    • Martin Wimmer
    • , Alois Regensburger
    •  & Ulf Peschel

  • Letter |

    The intensity of optically-pumped fluorescence generated from a single atomic defect in diamond can be reduced by 80% in just 100 ns by applying infrared laser light. This result demonstrates the possibility of using these so-called nitrogen–vacancy centres to create optical switches that operate at room temperature.

    • Michael Geiselmann
    • , Renaud Marty
    •  & Romain Quidant

  • Letter |

    A nanomechanical interface between optical photons and microwave electrical signals is now demonstrated. Coherent transfer between microwave and optical fields is achieved by parametric electro-optical coupling in a piezoelectric optomechanical crystal, and this on-chip technology could form the basis of photonic networks of superconducting quantum bits.

    • Joerg Bochmann
    • , Amit Vainsencher
    •  & Andrew N. Cleland

  • News & Views |

    A relativistic electron beam travelling on an undulating path interacts with a laser and emits light carrying orbital angular momentum. The wavelengths of these bright twisted-light beams can go down to those of hard X-rays.

    • Marie-Emmanuelle Couprie

  • Letter |

    The interaction between light and a relativistic electron beam can be used to generate optical vortices in a free electron laser, providing a way to engineer bright orbital angular momentum light at shorter X-ray wavelengths.

    • Erik Hemsing
    • , Andrey Knyazik
    •  & James B. Rosenzweig

  • News & Views |

    Distinguishing between different sources of noise in quantum dots could help to develop single-photon devices that are suitable for long-range entanglement.

    • Hendrik Bluhm

  • Article |

    Charge noise and spin noise lead to decoherence of the state of a quantum dot. A fast spectroscopic technique based on resonance fluorescence can distinguish between these two deleterious effects, enabling a better understanding of how to minimize their influence.

    • Andreas V. Kuhlmann
    • , Julien Houel
    •  & Richard J. Warburton

  • News & Views |

    Transformation optics is an invaluable tool for designing metamaterials. The same idea, it is now shown, could also prove to be a boon for nanoplasmonics.

    • R. C. McPhedran

  • Article |

    The modelling of plasmonic systems is complicated by the broad range of length scales involved: the physical dimensions of the structure might be as small as 1 nm, whereas the wavelength of the light involved can be a few hundred nanometres. It is now shown that transformation optics, a technique successfully used to design metamaterials, is also valuable for circumventing these problems.

    • J. B. Pendry
    • , A. I. Fernández-Domínguez
    •  & Rongkuo Zhao

  • News & Views |

    A planar composite material images ultraviolet light like a lens, by unwinding its phase. The concept could aid high-resolution nanolithography.

    • Rupert F. Oulton
    •  & John B. Pendry

  • News & Views |

    Usually a laser consists of a light-amplifying medium nested between two mirrors. A mirrorless laser that operates by forcing the light to take a long, random path through the gain medium has now been demonstrated.

    • Vladan Vuletic

  • Letter |

    Random lasing, where light is amplified through multiple scattering in a gain medium, could occur naturally in astrophysical environments. Experimental evidence for random lasing in a cloud of cold atoms may lead to a better understanding of these astrophysical lasers.

    • Q. Baudouin
    • , N. Mercadier
    •  & R. Kaiser

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