Tri-Level Echoes

Abstract

We report a new Doppler-free rephasing effect, the tri-level echo, which we use to study Ar-Na collisional relaxation of several 3^Si/2-w^D3/2 superpositions in atomic Nao Three excitation pulses are required: The first resonantly excites a selected state, while the others resonantly couple this state with a higher-lying state. This sequence produces a delayed rephasing on the resonance transition which radiates strongly; the radiated intensity monitors relaxation in the higher-lying stepwise-excited state.It is well known that an echo, i. e. , a rephasing of superposition states, may be formed in a sample of inhomogeneously broadened two-level systemSo First observed by Hahn in spin systems (spin echoes)^ and later by Abella, Kurnit, and Hartmann in systems of electronic states (photon echoes),^ these two-level single-frequency echoes have proven useful in the study of homogeneous relaxation. This basic phenomenon has recently been extended by the observation^ of the Raman echo,^ which is similar to the photon echo except that the two states are connected by a two-photon interaction matrix element. In this Letter we present a new type of echo peculiar to multilevel (three levels or more) systems. We have discovered that for a sample of multilevel systems inhomogeneously broadened by the Doppler effect^ a rephasing of a coherent superposition between a particular pair of levels can be induced even if the constituent systems of the sample spend most of the time between their first excitation and the echo dephasing in a superposition between a different pair of levels. The echo signals produced are large since they arise on an allowed transition. Through them one can study the relaxation of a step-wise, resonantly excited superposition which would ordinarily be inaccessible. We term this effect tri-level echoes. Similar effects were predicted several years ago by Aihara and Inaba,^ who described them as anomalous photon echoes. Related effects were observed in three-level spin systems by Hatanaka, Terao, and Hashi. ' We have observed tri-level echoes in Na on the i^S^,^-3^^

Collision-induced stimulated photon echo at the transition 0–1

“…The modified stimulated photon echo [16,17] is formed when the first two excitation pulses are in resonance with some optically-allowed transition a → b, while the third pulse is in resonance with some adjacent transition b → c. This echo signal is perfectly suited for the measurement of relaxation characteristics of the intermediate level b [18]. Another type of echo, which may be generated in a three-level system by three excitation pulses is the tri-level echo [19]. This echo is formed, when the first and the third excitation pulses are in resonance with one of the two optically-allowed transitions a → b sharing common level a, while the second pulse is in resonance with the other transition a → c. Such echoes provide information about the relaxation characteristics of the optically-forbidden transition b → c [20].…”

Dynamical symmetry breaking of lambda- and vee-type three-level systems on quantization of the field modes

“…The two-level system is modeled using the Pauli's spin matrices -the spin-half representation of SU (2) group, where apart from the level number, the spectrum is designated by the photon number as the quantum number. A natural but non-trivial extension of the JCM is the three-level system and it exhibits plethora of optical phenomena such as, two-photon coherence [6], resonance Raman scattering [7], double resonance process [8],population trapping [9], three-level super radiance [10], three-level echoes [11], STIRAP [12], quantum jump [13], quantum zeno effect [14], Electromagnetically Induced Transparency [15,16] etc. There are three distinct schemes of the three-level configurations which are classified as the lambda, vee and cascade systems respectively.…”

Multidimensional raman spectroscopy

“…for the second time period. Thus, fifth-order spectroscopy is similar to the tri-level echo in electronic spectroscopy [93]. However, unlike in the case of the Raman echo and other nonlinear techniques, the pathways that do not have echo-like behavior cannot be removed using phase-matching tricks, and so the echo necessarily competes with these other processes in the signal.…”