This PDF file contains the front matter associated with SPIE
Proceedings Volume 6906, including the Title Page, Copyright
information, Table of Contents, Introduction (if any), and the
Conference Committee listing.
The frequency comb of an optical resonator is a naturally large set of exquisitely well defined quantum systems,
such as in the broadband mode-locked lasers which have redefined time/frequency metrology and ultraprecise
measurements in recent years. High coherence can therefore be expected in the quantum version of the frequency
comb, in which nonlinear interactions couple different cavity modes, as can be modeled by different forms of graph
states. We show that is possible to thereby generate states of interest to quantum metrology and computing,
such as multipartite entangled cluster and Greenberger-Horne-Zeilinger states.
It is known that the phase measurement using lossless Mach-Zehnder interferometer with certain entangled
N-photon states can achieve a phase sensitivity of the order of 1/N, the Heisenberg limit. However, the output
observable used is different for different input states to achieve the Heisenberg limit. In this paper, we show
that it is possible to achieve this limit just by parity measurement for all the commonly proposed entangled
states. Taking account of path absorption effect, the phase shifts with parity measurement for these states are
obtained and indicate that the N00N state still remains to be the best candidate to perform phase detection if the
transmittance of the medium is not too small and the number of photons is not very large.
We report observation of high contrast Raman-Ramsey fringes using time delayed optical pulse pairs in a rubidium
vapor cell. The width of these fringes are not limited by saturation and provides a simpler means to produce narrow
atomic linewidths using a thermal vapor medium for compact atomic clock applications. We also demonstrate phasescanned
Raman-Ramsey fringes, with potential application to sensitive detection of trace vapors.
The end-resonance clock uses strong hyperfine end transition to stabilize the frequency of the local oscillator.
Comparing to the conventional 0-0 atomic clock, end resonance has very small spin-exchange broadening effect. The
spin-exchange rate is proportional to the number density of the alkali-metal atoms. By using the end resonance, we are
able to use very high dense vapor to obtain a much better signal to noise ratio. On the other hand, the end resonance
suffers from the first-order magnetic field dependence. This problem, however, can be solved by simultaneously using a
Zeeman end resonance to stabilize the magnetic field. Here, we report the most recent result of the end-resonance clock.
In addition, we report a whole new technique, push-pull laser-atomic oscillator, which can be thought as all-photonic
clock. This new clock requires no local oscillator. It acts like a photonic version of maser, which spontaneously
generates modulated laser light and modulated voltage signals. The modulation serves as the clock signal, which is
automatically locked to the ground-state hyperfine frequency of alkali-metal atoms.
We analyze the phase estimation ability of photonic N00N states propagating in a lossy medium. In such a
medium a N00N state of N enangled photons cannot achieve the maximum 1/N phase estimation resolution.
In fact, unless the transmittance of the medium is extremely high, a signal comprised of an attenuated separable
state of N photons will produce a better phase estimate than a comparable signal of an equally attenuated N00N
state. Thus, for most practical applications the resolution provided photonic N00N states is actually worse than
the 1/√N Standard Quantum Limit. This performance deficit becomes more pronounced as the number of
photons in the signal increases.
In this paper, we study theoretically a zero-area Sagnac ring laser gravitational wave (GW) detector. We review first the
zero-area Sagnac interferometer for GW detection, comparing its properties against the more conventional GW detector
based on a Michaelson interferometer. We then describe a modified version of such a detector where the Sagnac
interferometer is replaced by a zero-area Sagnac ring resonator fed by an external laser. This leads to the description of a
GW detector based on an active, zero-area Sagnac ring resonator, where a gain medium is present inside the cavity.
Finally, we show that if a medium with negative dispersion, which yields the so-called fast-light effect, is also present
inside this detector, then its sensitivity to GW strain is enhanced by the inverse of the group index of the dispersive
medium. We describe conditions under which this enhancement factor could be as large as 105.
Radiation pressure exerted by light in interferometric measurements is responsible for displacements of mirrors
which appear as an additional back-action noise and limit the sensitivity of the measurement. We experimentally
study these effects by monitoring in a very highfinesse optical cavity the displacements of a mirror with
a sensitivity at the 10-20 m/√Hz level. This unique sensitivity is a step towards the first observation of the
fundamental quantum effects of radiation pressure and the resulting standard quantum limit in interferometric
measurements. Our experiment may become a powerful facility to test quantum noise reduction schemes,
and we already report the first experimental demonstration of a back-action noise cancellation. Using a classical
radiation-pressure noise to mimic the quantum noise of light, we have observed a drastic improvement of
sensitivity both in position and force measurements.
General requirements for single-photon devices in various applications are presented and compared with experimental
progress to date. The quantum information applications that currently appear the most promising require
a matter qubit-enabled single-photon source, where the emitted photon state is linked to the state of a long-lived
quantum system such as an electron spin. The nitrogen-vacancy center in diamond is a promising solid-state
system for realizing such a device due to its long-lived electron spin coherence, optical addressability, and ability
to couple to a manageable number of nuclear spins. This system is discussed in detail, and experimental results
from our laboratory are shown. A critical component of such a device is an optical microcavity to enhance the
coupling between the nitrogen-vacancy center and a single photon, and we discuss theoretically the requirements
for achieving this enhancement.