טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSagi Yoav
SubjectOptical Interference with Non Coherent States
DepartmentDepartment of Physics
Supervisors Professor Emeritus Amiram Ron
Dr. Amnon Fisher


Abstract

In this work we consider the problem of two cavities, a 50%-50% beam splitter and detectors. We describe the Monte-Carlo Wave Functions (MCWF) method, which simulates one possible result of a continuous measurement process. We present the MCWF results for the two cavities setup, and show that even when the cavities are initially in Fock states, the detectors' readings exhibit a 100% visibility interference in a single trajectory (single MCWF run), as if the cavities were initially in coherent states. Next, we analyze the setup using the non-stochastic Langevin method. The expectation values for the detectors' readings are found to exhibit interference with varying visibility for many highly non-coherent states. In the case where the cavities are initially in Fock states no interference is apparent in the expectation values. Nevertheless, by second order correlation function analysis we show that there is a strong indication of interference in every experimental run even when the cavities are initially in a Fock states.

The main difficulty in realizing the setup considered is the creation of Fock states in the cavities with a large number of photons. We propose a realistic realization of the two cavities setup, which conserves the interesting characteristics of the original setup, but avoids this difficulty.

Finally, we propose a more general explanation for the coherent-like behavior of non-coherent states by employing the spontaneously broken symmetry technique. We postulate that continuous measurements or even small losses in the optical components play the role of a phase symmetry breaking field which collapses the state of the system to a specific coherent state with a definite phase.