25 research outputs found
General Formalism for Evaluating the Impact of Phase Noise on Bloch Vector Rotations
Quantum manipulation protocols for quantum sensors and quantum computation
often require many single qubit rotations. However, the impact of phase noise
in the field that performs the qubit rotations is often neglected or treated
only for special cases. We present a general framework for calculating the
impact of phase noise on the state of a qubit, as described by its equivalent
Bloch vector. The analysis applies to any Bloch vector orientation, and any
rotation axis azimuthal angle for both a single pulse, and pulse sequences.
Experimental examples are presented for several special cases. We apply the
analysis to commonly used composite -pulse sequences: CORPSE, SCROFULOUS,
and BB1, used to suppress static amplitude and detuning errors, and also to
spin echo sequences. We expect the formalism presented will help guide the
development and evaluation of future quantum manipulation protocols.Comment: 12 pages, 6 figures, submitted to PR
Relaxation oscillations, stability, and cavity feedback in a superradiant Raman laser
We experimentally study the relaxation oscillations and amplitude stability
properties of an optical laser operating deep into the bad-cavity regime using
a laser-cooled Rb Raman laser. By combining measurements of the laser
light field with nondemolition measurements of the atomic populations, we infer
the response of the gain medium represented by a collective atomic Bloch
vector. The results are qualitatively explained with a simple model.
Measurements and theory are extended to include the effect of intermediate
repumping states on the closed-loop stability of the oscillator and the role of
cavity feedback on stabilizing or enhancing relaxation oscillations. This
experimental study of the stability of an optical laser operating deep into the
bad-cavity regime will guide future development of superradiant lasers with
ultranarrow linewidths.Comment: 9 pages, 6 figure