The outcome of a light-matter interaction depends on both the state of matter and the state of light. It is thus a natural setting for implementing bilinear classical logic. A description of the state of a time-varying system requires measuring an (ideally complete) set of time-dependent observables. Typically, this is prohibitive, but in weak-field spectroscopy we can move toward this goal because only a finite number of levels are accessible. Recent progress in nonlinear spectroscopies means that nontrivial measurements can be implemented and thereby give rise to interesting logic schemes where the outputs are functions of the observables. Lie algebra offers a natural tool for generating the outcome of the bilinear light-matter interaction. We show how to synthesize these ideas by explicitly discussing three-photon spectroscopy of a bichromophoric molecule for which there are four accessible states. Switching logic would use the on-off occupancies of these four states as outcomes. Here, we explore the use of all 16 observables that define the timeevolving state of the bichromophoric system. The bilinear lasersystem interaction with the three pulses of the setup of a 2D photon echo spectroscopy experiment can be used to generate a rich parallel logic that corresponds to the implementation of a molecular decision tree. Our simulations allow relaxation by weak coupling to the environment, which adds to the complexity of the logic operations.finite-state machines | Shannon decomposition | parallel multivalued logic | quaternary logic T he need to further reduce the physical dimensions of a computing node is well recognized (1-4). A direct way to go below a nanometer scale is to use a molecule or an artificial atom-a quantum dot-as a switch (5-11). Molecules can also respond in more interesting ways than switching. So for some time we have followed a program of seeking to implement an entire logic circuit on an atom or molecule and to concatenating such units. To do so, we used intramolecular dynamics resulting from the response of a molecule to a perturbation-the inputs to the computationthat can be electrical (12) or optical (13) or chemical (14), etc. In principle, such an approach can implement finite-state logic (15) because typically the response of a molecule depends on its initial state as well as on the applied perturbation.In finite-state machines, the execution of the logic relies on transitions between states. The operation is inherently parallel (15). A simple situation is when a molecule relaxes after being perturbed by an optical (16,17) or an electrical pulse (18,19). In optical molecular implementations, several states can be simultaneously addressed, which leads to massively parallel linear finitestate machines (16,17). The other mode of operation is to provide inputs at each machine cycle. If the molecule is switched between two states, the ability to encode a dependence on the initial state means that one can implement memristor logic (20). More elaborated memory integrated units like set-reset ...

To realize low‐power, compact logic circuits, one can explore parallel operation on single nanoscale devices. An added incentive is to use multivalued (as distinct from Boolean) logic. Here, we theoretically demonstrate that the computation of all the possible outputs of a multivariate, multivalued logic function can be implemented in parallel by electrical addressing of a molecule made up of three interacting dopant atoms embedded in Si. The electronic states of the dopant molecule are addressed by pulsing a gate voltage. By simulating the time evolution of the non stationary electronic density built by the gate voltage, we show that one can implement a molecular decision tree that provides in parallel all the outputs for all the inputs of the multivariate, multivalued logic function. The outputs are encoded in the populations and in the bond orders of the dopant molecule, which can be measured using an STM tip. We show that the implementation of the molecular logic tree is equivalent to a spectral function decomposition. The function that is evaluated can be field‐programmed by changing the time profile of the pulsed gate voltage.

Employing the master equation for a three-level laser driven by coherent light and coupled to a squeezed vacuum reservoir, we obtain stochastic differential equations associated with the normal ordering. Using the solutions of the stochastic differential equations, we calculate the quadrature variance, the squeezing spectrum, the mean photon number, and the variance of the photon number. It turns out that the degree of squeezing increases with the linear gain coefficient or the squeeze parameter. It is also found that the driving coherent light decreases the mean photon number.Usage Secondary publications and information retrieval purposes.PACS numbers May be entered using the \pacs{#1} command.Structure You may use the description environment to structure your abstract; use the optional argument of the \item command to give the category of each item.

This work investigates the effect of phonon coupling on the transfer of population and creation of coherence using variant of stimulated Raman adiabatic passage (STIRAP) known as fractional stimulated Raman adiabatic passage (FSTIRAP). The study is based on the Liouville equation, which is solved numerically in the adiabatic limit. Although the phonon is assumed to be coupled only to the intermediate state, it is coupled to the other two states by dipolar system-environment interaction, inducing phonon coupling to the other states which are not directly in contact with the phonon. At zero temperature the STIRAP pulse protocol's efficiency of the transfer decreases exponentially with the electron-phonon coupling, until the coupling strength is strong enough to make the process fully incoherent, in which case the population transfer is 1 3 in each level. For the FSTIRAP protocol we find that the transferred population to target state decreases, leaving some population on the intermediate state. Consequently, there is an increase in the magnitude of the coherences ρ01, ρ12, albeit small. Furthermore population transfer for non-zero temperature and effect of coupling strength is investigated, it is observed that while both parameters negatively influence the efficiency of transfer the former decrease the transfer exponentially, thereby equilibrating the system fast, while the latter seen to decrease the transfer monotonically, and hence equilibrates slowly.