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We report the photon-number squeezing of optical solitons. 2.7 ps pulses were launched as solitons down a 1.5 km optical fiber. For energies slightly above that of fundamental solitons, they broadened spectrally due to self-phase modulation caused by x ͑3͒ nonlinearities. Filtering away outlying components of the broadened spectra squeezed the soliton's photon-number fluctuations to 2.3 dB (41%) below the shot-noise limit. Accounting for losses, this corresponds to 3.7 dB (57%) photon-number squeezing. A quantum field-theoretic model shows that the outlying spectral components have large energy fluctuations, so that their removal causes squeezing.[S0031-9007 (96)01512-8] PACS numbers: 42.50.Dv, 42.50.Ar, 42.65.Tg, 42.81.DpAn optical soliton in an optical fiber acts as a "particle" of light, according to classical electrodynamics, and can propagate long distances without changing shape or losing energy. Its particlelike nature is robust-a soliton is insensitive to perturbations and undistorted by collisions with other solitons. This, understandably, has practical implications and soliton-based telecommunication technologies are actively being pursued [1].A classical electrodynamical description of soliton propagation is inadequate if a soliton's quantum mechanical properties are of interest. Quantum mechanical descriptions not only better describe a soliton's noise properties, but also predict the existence of unique quantum mechanical soliton effects [2][3][4][5][6][7][8][9]. Most of the desirable properties of classical optical solitons, including their particlelike nature, are retained by such quantum mechanical descriptions [2-4].The first quantum mechanical soliton effect to be observed experimentally was quadrature-amplitude squeezing, predicted by Carter et al. [5,6]. For such squeezing, soliton amplitudes can fluctuate with magnitudes either smaller or greater than the standard quantum limit (SQL) of coherent light pulses, depending on the measured phase [5]. The "entanglement" of two solitons makes quantum nondemolition measurements possible, and was the second quantum mechanical soliton effect to be observed [7]. As described by Haus et al., two solitons with different velocities become quantum mechanically entangled when they collide [8]. A measurement of the phase of one soliton then allows the photon number of the other soliton to be determined without introducing losses or photonnumber noise.Recently, we have observed an unanticipated new quantum mechanical soliton effect-soliton photon-number squeezing [9]. By removing a soliton's outlying spectral components with a spectral bandpass filter, we were able to reduce its photon-number fluctuations to as much as 2.3 dB (41%) below the SQL. (For photon-number squeezing, the SQL is the usual shot-noise limit for coherent pulses of light.) Accounting for measurement losses and imperfect detector efficiencies, this implies a total photon-number squeezing of 3.7 dB (57%). Only squeezed light generation using a cw semiconductor laser at 66 K has produced phot...

Planar auxetic structures have the potential to impact on a wide range of applications from deployable and morphing structures to space-filling composite and medical treatments. The ability to fabricate auxetics from smart materials greatly enhances this facility by building in controllable actuation and deployment. A smart auxetic device can be compressed and fixed into a storage state. When deployment is required the device can be appropriately stimulated and the stored elastic energy is released, resulting in a marked structural expansion. Instead of using a conventional external actuator to drive deployment the material is made to undergo phase transition where one stimulus (e.g. heat) initiates a mechanical response. Here we show how smart material auxetics can be realized using a thermally responsive shape memory polymer composites. We show how a shape memory polymer auxetic hexachiral structure can be tailored to provide a tunable stiffness response in its fully deployed state by varying the angle of inter-hub connections, and yet is still able to undergo thermally stimulated deployment.

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