Juan F. Hodelin

Multiphoton Path Entanglement by Nonlocal Bunching

Multiphoton path entanglement is created without applying postselection, by manipulating the state of stimulated parametric down-conversion. A specific measurement on one of the two output spatial modes leads to the nonlocal bunching of the photons of the other mode, forming the desired multiphoton path entangled state. We present experimental results for the case of a heralded two-photon path entangled state and show how to extend this scheme to higher photon numbers.

Enhanced photogenerated carrier collection in hybrid films of bio-templated gold nanowires and nanocrystalline CdSe.

Hybrid films of bio-templated gold nanowires and chemical bath deposited nanocrystalline CdSe were fabricated. The conductivity of the gold nanowires within the hybrid material was controlled by gold electroless deposition. Photocurrent measurements were taken on gold nanowire films, CdSe chemical bath deposited films, and hybrid films. The incorporation of gold nanowires within the hybrid material clearly increased the extraction of photogenerated carriers within the CdSe. Photocurrent showed a direct correlation with gold nanowire conductivity.

Realization of Hardy's thought experiment with photons.

We present an experimental realization of Hardys thought experiment [Phys. Rev. Lett. 68, 2981 (1992)], using photons. The experiment consists of a pair of Mach-Zehnder interferometers that interact through photon bunching at a beam splitter. A striking contradiction is created between the predictions of quantum mechanics and local hidden variables. The contradiction relies on nonmaximally entangled position states of two particles. A Clauser-Horne-type inequality is derived and violated.

Optimal generation of pulsed entangled photon pairs

We experimentally investigate a double-pass parametric down-conversion scheme for producing pulsed, polarization-entangled photon pairs with high visibility. The amplitudes for creating photon pairs on each pass interfere to compensate for distinguishing characteristics that normally degrade two-photon visibility. The result is a high-flux source of polarization-entangled photon pulses that does not require spectral filtering. We observe quantum interference visibility of over 95% without the use of spectral filters for 200 fs pulses, and up to 98.1% with 5 nm bandwidth filters.

Experimental phase detection at the quantum limit with coherent state interferometry

We experimentally demonstrate phase sensitivity at the standard quantum limit independent of phase using Bayesian phase estimation. This technique is unbiased and saturates the Cramer-Rao lower bound representing the optimum technique using coherent states.

Subwavelength interferometry using path entanglement and photon-number resolving detectors

We demonstrate subwavelength interference fringes using two methods. The first preselects path entangled states from parametric downconversion, and the second uses multiphoton detection of classical light.

Path entangled photons from parametric down-conversion

Using stimulated parametric down-conversion, we propose a method for generating multiphoton path entanglement. By a special coincidence detection at one down-converted arm, the photons of the second arm non-locally bunch into the desired state. Experimental demonstration for the case of two photons is presented, as well as how to extend the scheme to any number of photons.