Quantum correlated light beams from non-degenerate four-wave mixing in an atomic vapor: the D1 and D2 lines of ^85Rb and ^87Rb

R C Pooser,V Boyer,K M Jones,A M Marino,P D Lett

doi:10.1364/oe.17.016722

Abstract

We present experimental results showing that quantum correlated light can be produced using non-degenerate, off-resonant, four-wave mixing (4WM) on both the D1 (795 nm) and D2 (780 nm) lines of (85)Rb and (87)Rb, extending earlier work on the D1 line of (85)Rb. Using this 4WM process in a hot vapor cell to produce bright twin beams, we characterize the degree of intensity-difference noise reduction below the standard quantum limit for each of the four systems. Although each system approximates a double-lambda configuration, differences in details of the actual level structure lead to varying degrees of noise reduction. The observation of quantum correlations on light produced using all four of these systems, regardless of their substructure, suggests that it should be possible to use other systems with similar level structures in order to produce narrow frequency, non-classical beams at a particular wavelength.

Highlights

Since the early days of research on squeezed states of light [1], it has been appreciated that four-wave mixing (4WM) in an atomic vapor can produce non-classical states of light
Work on 4WM in atomic vapors has continued, as interest has broadened beyond single mode quadrature squeezing to quantum correlations between multiple beams
The fact that 85Rb and 87Rb differ in nuclear spin and magnetic moment, and in F values and hyperfine splittings, does not appear to be as important as the difference in level structure between the D1 and D2 lines

Summary

Introduction

Since the early days of research on squeezed states of light [1], it has been appreciated that four-wave mixing (4WM) in an atomic vapor can produce non-classical states of light. Achieving high levels of single mode quadrature squeezing in this way has, proved difficult even when cold atoms are used [2]. Work on 4WM in atomic vapors has continued, as interest has broadened beyond single mode quadrature squeezing to quantum correlations between multiple beams. Four-wave mixing in atomic vapors is a natural choice for producing such light. Proposals for using non-classical light to manipulate cold atoms have been put forth [10, 11] which require narrowband light near atomic resonance

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Discussion

Conclusion