Title :
What can we learn from two-dimensional optical Wigner functions?
Author :
Wu, J.-W. ; Lam, P.K. ; Gray, M.B. ; Bachor, H.-A.
Author_Institution :
Dept. of Phys., Australian Nat. Univ., Canberra, ACT, Australia
Abstract :
Summary form only given.We show experimentally the reconstructions of Wigner functions for the output states of a laser. These states have classical Wigner functions with Gaussian cross-sections. In order to investigate the spectral properties of the output states, we normalize the Wigner functions in the inverse Radon transform algorithm to a coherent state. In this way, we are able to compare the full spectrum of Wigner functions obtained with different detection frequencies, paying particular attention to Wigner functions near the laser relaxation oscillation. The same normalized Wigner function is also used to measure squeezed optical states from an optical parametric oscillator. When large modulation is introduced to the laser beam, a dc component is introduced in the Wigner function. We show that Wigner functions of incoherent superposition states can be reconstructed using this modulation technique. In some cases, fluctuations can be large enough to produce highly non-Gaussian Wigner functions. We provide examples of such cases and show that optical homodyne tomography can provide essentially new information not detectable with standard quadrature variance measurements. Furthermore, we demonstrate that single sideband analysis used to date will sometimes no longer suffice in the analysis of such optical states. We include the higher order sideband correlations experimentally and discuss the necessity of these higher order sidebands for measuring non-Gaussian quantum states, e.g. Schrodinger´s cat and Fock states.
Keywords :
Radon transforms; Schrodinger equation; Wigner distribution; laser beams; optical squeezing; optical tomography; quantum optics; 2D optical Wigner functions; DC component; Fock state; Gaussian cross-sections; Schrodinger cat state; coherent state; higher order sideband correlations; highly nonGaussian Wigner functions; incoherent superposition states; inverse Radon transform algorithm; large modulation; laser output states; laser relaxation oscillation; normalized Wigner function; optical homodyne tomography; optical parametric oscillator; quantum correlations; quantum statistics of light; reconstructions of Wigner functions; spectral properties; squeezed optical states; Atom lasers; Atom optics; Atomic beams; Cooling; Magnetic resonance; Nonlinear optics; Optical buffering; Optical modulation; Physics; Pulse measurements;
Conference_Titel :
Quantum Electronics Conference, 1998. IQEC 98. Technical Digest. Summaries of papers presented at the International
Conference_Location :
San Francisco, CA, USA
Print_ISBN :
1-55752-541-2
DOI :
10.1109/IQEC.1998.680248