Metin Sabuncu

Experimental demonstration of continuous variable cloning with phase-conjugate inputs

We report the experimental demonstration of continuous variable cloning of phase conjugate coherent states as proposed by Cerf and Iblisdir (Phys. Rev. Lett. 87, 247903 (2001)). In contrast to the proposal of Cerf and Iblisdir, the cloning transformation is accomplished using only linear optical components, homodyne detection and feedforward. Three clones are succesfully produced with fidelities about 89%.

Experimental demonstration of coherent state estimation with minimal disturbance

We investigate the optimal trade-off between information gained about an unknown coherent state and the state disturbance caused by the measurement process. We propose several optical schemes that can enable this task, and we implement one of them, a scheme that relies on only linear optics and homodyne detection. Experimentally we reach near optimal performance, limited only by detection inefficiencies. In addition, we show that such a scheme can be used to enhance the transmission fidelity of a class of noisy channels.

Quantum optical coherence can survive photon losses using a continuous-variable quantum erasure-correcting code

The effect of loss on quantum states is one of the major hurdles in quantum communications. A quantum error-correcting code that overcomes erasure due to photon loss is experimentally demonstrated. The scheme uses linear optics and protects a four-mode entangled mesoscopic state of light.

Generation of polarization squeezing with periodically poled KTP at 1064 nm.

We report the experimental demonstration of directly produced polarization squeezing at 1064 nm from a type I optical parametric amplifier (OPA) based on a periodically poled KTP crystal (PPKTP). The orthogonal polarization modes of the polarization squeezed state are both defined by the OPA cavity mode, and the birefringence induced by the PPKTP crystal is compensated by a second, but inactive, PPKTP crystal. Stokes parameter squeezing of 3.6 dB and anti squeezing of 9.4 dB is observed.

Experimental continuous-variable cloning of partial quantum information

The fidelity of a quantum transformation is strongly linked with the prior partial information of the state to be transformed. We illustrate this interesting point by proposing and demonstrating the superior cloning of coherent states with prior partial information. More specifically, we propose two simple transformations that under the Gaussian assumption optimally clone symmetric Gaussian distributions of coherent states as well as coherent states with known phases. Furthermore, we implement for the first time near-optimal state-dependent cloning schemes relying on simple linear optics and feedforward.

Superiority of entangled measurements over all local strategies for the estimation of product coherent states

It is shown that the ensemble

Environment-assisted quantum-information correction for continuous variables

\{p (\alpha),|\alpha>|\alpha^*>\}

A high-speed secure quantum random number generator based on vacuum states

where

Experimental demonstration of squeezed-state quantum averaging

p (\alpha)

Nonunity gain minimal-disturbance measurement

is a Gaussian distribution of finite variance and