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A quantum ‘tele-amplification’ scheme that combines teleportation and the noiseless amplification of a coherent state is demonstrated by using Schrödinger-cat states prepared by photon subtraction from squeezed vacuum as an entanglement resource. This scheme can realize high-capacity communication, thus beating the homodyne limit of optical communications.
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.
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.
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.
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.
Using two-way exchange between coherent frequency combs, each phase-locked to the local optical oscillator, optical time–frequency transfer is demonstrated in free space across a 2-km-long link, with a timing deviation of 1 fs, a residual instability below 10−18 at 1,000 s and systematic offsets below 4 × 10−19.
Focusing beyond the diffraction limit is achieved by using elastic light scattering from a highly turbid medium to convert propagating far-field components into near-field wave vectors. This finding may open new avenues for the subwavelength control of light, with applications in nanolithography and the interconnection between nanoelectronics and nanophotonics.
A scheme for overcoming the diffraction limit in the far-field imaging of non-fluorescent species is demonstrated. This technique, which is based on the spatially controlled saturation of electronic absorption, may enable the super-resolution imaging of nanomaterials and non-fluorescent chromophores.
A three-dimensional spectroscopic sensor is demonstrated that uses a polarization-resolved scattering technique to determine the location and orientation of small particles. It exploits strong Fano resonance between a pair of particles, one barely visible and another that is relatively bright, to obtain nanoscale orientation information.
In vivo, high-resolution, deep-tissue imaging of biological tissue is made possible by three-dimensional interferometric synthetic aperture microscopy. The method operates in real time and provides improved depth of field and resolution compared with conventional forms of optical coherence tomography.
Researchers demonstrate continuous-variable quantum key distribution over 80 km of optical fibre. They develop a detection system based on homodyne detectors to achieve an unprecedented level of stability and implement new codes tailored to perform secure communication optimally in a range of signal-to-noise ratios corresponding to long distances.
Researchers demonstrate bandwidth compression of single photons from 1740 GHz to 43 GHz, and tuning the center wavelength from 379 nm to 402 nm. The scheme relies on sum-frequency generation with frequency-chirped laser pulses. This technique enables interfacing between different quantum systems whose absorption and emission spectral properties are mismatched.
Researchers demonstrate the feasibility of BB84 quantum key distribution between a plane and a ground station. Establishing a stable, low-noise quantum communication channel with the plane moving at 290 km/h over a distance of 20 km (4 mrad s−1), the results are representative for typical communication links to satellites.
Researchers realize a quantum logic gate by performing all-optical coherent control of the exciton states of an InAs quantum dot in a photonic crystal cavity in the strong-coupling regime. Their demonstrations represent an important step towards realizing robust and scalable quantum networks and generating strong photon-photon interactions.
Researcher reports data transmission in 37 × 40 Gbit s−1 channels at 99.7% of the speed of light in vacuum in a fundamentally improved hollow-core photonic bandgap fibre with a record low loss of 3.5 dB km−1 and a wide bandwidth of 160 nm.
Researchers obtain bright visible light emission from silicon coupled with plasmon nanocavities due to non-thermal carrier recombination. The team reports an enhanced emission quantum efficiency and the concept is promising for developing monolithically integrated light sources on conventional microchips.
Shot noise originates from the discrete nature of optical field detection. By exploiting correlations in the shot-noise spectrum of optical pulse trains, scientists improve shot-noise-limited optical pulse timing measurements by several orders of magnitude. A photodetected pulse train timing noise floor at an unprecedented 25 zs Hz−1/2 is reported.
Researchers develop a fiber-coupled single-photon-detection system using amorphous tungsten silicide superconducting nanowire single-photon detectors. The system detection efficiency is higher than 90% in the wavelength range between 1520 nm and 1610 nm. The device dark-count rate, timing jitter and reset time are 1 cps, 150 ps and 40 ns, respectively.
By taking advantage of free-carrier generation in optically transparent media researchers have improved synchronization between optical lasers and free-electron laser pulses. This technique has an optical/X-ray delay with a sub-10 fs r.m.s error.
By combining the techniques of temporal focusing and generalized phase contrast researchers are able to preserve the shape of spatial patterns of light deep inside scattering brain slices. This approach is shown to photoactivate the light-sensitive protein channelrhodopsin-2 with single-cell precision and millisecond temporal resolution.
