Weak signal detection using coherent control

Phase sensitive coherent control of atomic excitation in the presence of static electric fields: a frame transformation Stark theory approach

“…For the ω-beam, it is further assumed that there are no exactly-or near-resonant intermediate states in the vicinity of the first photon. Detection of excited atoms may be achieved by collecting the fluorescence emitted during the final level's radiative decay [13,14] or by ionization [15]. The latter occurs either because the excitation energy lies above ε sp or, when ε < ε sp , because the atoms absorb an additional photon from the laser beam responsible for the two-photon transition.…”

“…For overcoming the above-mentioned parity and selection rule restrictions on the control of total atomic excitation/ionization rates, early theoretical suggestions [12] implicated external static electric fields, mixing states of opposite parity. Experimentally however, the concept was implemented only recently [13][14][15] and by adopting excitation schemes differing with respect to that proposed in [12]. In one of these studies [13,14], phase control was achieved using the cesium 6s→8s transition.…”

“…Experimentally however, the concept was implemented only recently [13][14][15] and by adopting excitation schemes differing with respect to that proposed in [12]. In one of these studies [13,14], phase control was achieved using the cesium 6s→8s transition. In the absence of a static electric field only two-photon excitation is possible.…”

“…Then, a weak one-photon dipole transition amplitude is induced, simulating feeble electric quadrupole, magnetic dipole and parity nonconserving interactions. Theoretically, the weakness of this mixing permitted the approximation that the p-character admixture coefficient of the final 8s state varies linearly with the static field's strength [14]. The other experimental work demonstrated phase control over the population (and subsequent ionization) of Stark 5sεk Rydberg states of strontium, below as well as above the saddle point energy [15].…”

Gain measurement scheme for precise determination of atomic parity violation through two-pathway coherent control

“…More recently, our group has developed a two-color coherent control scheme where an additional laser is added to "strongly" excite the weak transitions. This technique displayed shotnoise-limited detection in measurements of a weak 6S 1/2 → 8S 1/2 Stark-induced transition [31,32], and was used to measure the magnetic dipole moment M 1 on the 6S 1/2 → 7S 1/2 transition [33,34] in cesium. We are also working on a two-color optical and rf interference experiment to directly probe the NSD interaction in the cesium ground hyperfine states [35].…”