© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

arXiv:0910.3799

Femtosecond Photo-Induced Multiphoton Analog Computation for Symmetry-Based Pattern Classification

Lev Chuntonov, Leonid Rybak, Andrey Gandman, Zohar Amitay

Published Oct 20, 2009• 0 citations

Abstract

Multiphoton femtosecond coherent control of is used for implementing innovative photo-induced analog coherent computation that generally might be a basis for future "smart hardware". The specific implemented computational task the classification of an unknown sequence into one of the three groups: (i) a constant sequence that is composed of identical numbers, (ii) a sequence that is antisymmetric around a given point, or (iii) neither. The input sequence is encoded into the spectral phases of a broadband femtosecond pulse and the computational task is being carried out by the multiphoton nonlinear response of the irradiated physical system. Here, it is the simultaneous coherent two- and three-photon absorption in atomic sodium (Na). The corresponding computational resources are the manifold of initial-to-final multiphoton excitation pathways photo-induced by the broad spectrum of the irradiating femtosecond pulse. The answer is obtained by measuring only two observables, which are two state-populations excited via the two- and three-photon absorption processes. Hence, the computational task is accomplished in a constant number of operations irrespective of the sequence length. As such, the presented scheme, where the femtosecond pulse serves as a query and the irradiated physical system serves as an oracle, provides a sufficient gain in the computational complexity.

DOI: 10.48550/arxiv.0910.3799

Related papers

Observation and Symmetry-Based Coherent Control of Transient Two-Photon Absorption: The Bright Side of Dark Pulses

Andrey Gandman, Leonid Rybak, Zohar Amitay

We present and experimentally demonstrate for the first time the observation and femtosecond coherent control over the temporal evolution of a transient population that is excited via nonresonant two-photon absorption. Based on symmetry properties of the two-photon absorption process, the exciting femtosecond pulses are phase-shaped to photoinduce different evolutions of the transient excited population for a given final excited population. As a study case, we focus here on the attractive case of two-photon dark pulses that, although inducing zero final population (hence, the terminology of "dark pulses"), they induce a transient excited population during the pulse irradiation that can significantly deviate from zero. This nonzero transient population can be viewed as the bright side of such dark pulses. The symmetry-based coherent control is demonstrated first with dark pulses that we shape to induce transient excited population that at all times is kept below different target levels. Then, it is further demonstrated with pairs of dark pulses where one is rationally shaped to induce temporal evolution of the transient excited population that is the inverse of the evolution induced by the other. The work is conducted in the weak-field regime with the sodium atom as the model system. The approach developed here is general, conceptually simple, and very effective.

Physical Review Letters•Jul 23, 2014•6 citations

Symmetry-Based Selective Femtosecond Coherent Control of Transient Two-Photon Absorption

Andrey Gandman, Leonid Rybak, Bronstein, Michal +2 more

We present and implement a new scheme for independent control of both the final and the transient population utilizing the symmetry properties of the system. By proper pulse shaping, utilizing the invariance of the two-photon absorption to specific phase transformations of the pulse, different time evolutions of the transient population are photo-induced for a given (fixed) final state population. The model system is the Na atom. The work is conducted in the weak-field regime for which the transient two-photon excitation is described by second-order perturbation theory. One most attractive case is the extended family of third-order chirp pulses which control the population build-up duration independently of the final population.

arXiv:0910.3581•Oct 19, 2009•0 citations

Weak-field multiphoton femtosecond coherent control in the single-cycle regime

Lev Chuntonov, Avner Fleischer, Zohar Amitay

Weak-field coherent phase control of atomic non-resonant multiphoton excitation induced by shaped femtosecond pulses is studied theoretically in the single-cycle regime. The carrier-envelope phase (CEP) of the pulse, which in the multi-cycle regime does not play any control role, is shown here to be a new effective control parameter that its effect is highly sensitive to the spectral position of the ultrabroad spectrum. Rationally chosen position of the ultrabroadband spectrum coherently induces several groups of multiphoton transitions from the ground state to the excited state of the system: transitions involving only absorbed photons as well as Raman transitions involving both absorbed and emitted photons. The intra-group interference is controlled by the relative spectral phase of the different frequency components of the pulse, while the inter-group interference is controlled jointly by the CEP and the relative spectral phase. Specifically, non-resonant two- and three-photon excitation is studied in a simple model system within the perturbative frequency-domain framework. The developed intuition is then applied to weak-field multiphoton excitation of atomic cesium (Cs), where the simplified model is verified by non-perturbative numerical solution of the time-dependent Schrödinger equation. We expect this work to serve as a basis for a new line of femtosecond coherent control experiments.

Optics Express•Mar 25, 2011•6 citations

Coherent phase control of resonance-mediated (2+1) three-photon absorption

Andrey Gandman, Lev Chuntonov, Leonid Rybak +1 more

Femtosecond coherent phase control of resonance mediated $(2+1)$ three-photon absorption is studied both theoretically and experimentally. The regime is perturbative of third order. The photoexcitation coherently combines elements of both nonresonant and resonance-mediated multiphoton transitions. By proper simple pulse shaping the three-photon absorption in Na is effectively controlled experimentally, enhanced up to $\ensuremath{\sim}300%$ of the absorption induced by the transform-limited pulse. It is achieved by phase manipulating intra- and intergroup interferences involving two groups of three-photon excitation pathways: (i) on resonance and (ii) near resonance with the intermediate resonance state accessed by nonresonant two-photon transition.

Physical Review A•Mar 9, 2007•70 citations

Multichannel Selective Femtosecond Coherent Control Based on Symmetry Properties

Zohar Amitay, Andrey Gandman, Lev Chuntonov +1 more

We present and implement a new scheme for extended multichannel selective femtosecond coherent control based on symmetry properties of the excitation channels. Here, an atomic nonresonant two-photon absorption channel is coherently incorporated in a resonance-mediated (2+1) three-photon absorption channel. By proper pulse shaping, utilizing the invariance of the two-photon absorption to specific phase transformations of the pulse, the three-photon absorption is tuned independently over an order-of-magnitude yield range for any possible two-photon absorption yield. Noticeable is a set of "two-photon dark pulses" inducing widely tunable three-photon absorption.

arXiv:0710.0149•Physical Review Letters•May 16, 2008•40 citations

Multiphoton Femtosecond Control of Resonance-Mediated Generation of Short-Wavelength Coherent Broadband Radiation

Leonid Rybak, Lev Chuntonov, Andrey Gandman +2 more

We introduce a new scheme for generating short-wavelength coherent broadband radiation with well-controlled spectral characteristics. It is based on shaping long-wavelength femtosecond pulse to coherently control atomic resonance-mediated (2+1) three-photon excitation to a broad far-from-resonance continuum. Here, the spectrum (central frequency and bandwidth) of deep-ultraviolet coherent broadband radiation generated in Na vapor is experimentally controlled by tuning the linear chirp we apply to the driving phase-shaped near-infrared femtosecond pulse. This is a first step in implementing the full scheme for producing shaped femtosecond pulses at wavelengths down-to the vacuum-ultraviolet range.

arXiv:0910.3526•Oct 19, 2009•0 citations

Multiphoton femtosecond coherent control of is used for implementing innovative photo-induced analog coherent computation that generally might be a basis for future "smart hardware". The specific implemented computational task the classification of an unknown sequence into one of the three groups: (i) a constant sequence that is composed of identical numbers, (ii) a sequence that is antisymmetric around a given point, or (iii) neither. The input sequence is encoded into the spectral phases of a broadband femtosecond pulse and the computational task is being carried out by the multiphoton nonlinear response of the irradiated physical system. Here, it is the simultaneous coherent two- and three-photon absorption in atomic sodium (Na). The corresponding computational resources are the manifold of initial-to-final multiphoton excitation pathways photo-induced by the broad spectrum of the irradiating femtosecond pulse. The answer is obtained by measuring only two observables, which are two state-populations excited via the two- and three-photon absorption processes. Hence, the computational task is accomplished in a constant number of operations irrespective of the sequence length. As such, the presented scheme, where the femtosecond pulse serves as a query and the irradiated physical system serves as an oracle, provides a sufficient gain in the computational complexity.

We present and experimentally demonstrate for the first time the observation and femtosecond coherent control over the temporal evolution of a transient population that is excited via nonresonant two-photon absorption. Based on symmetry properties of the two-photon absorption process, the exciting femtosecond pulses are phase-shaped to photoinduce different evolutions of the transient excited population for a given final excited population. As a study case, we focus here on the attractive case of two-photon dark pulses that, although inducing zero final population (hence, the terminology of "dark pulses"), they induce a transient excited population during the pulse irradiation that can significantly deviate from zero. This nonzero transient population can be viewed as the bright side of such dark pulses. The symmetry-based coherent control is demonstrated first with dark pulses that we shape to induce transient excited population that at all times is kept below different target levels. Then, it is further demonstrated with pairs of dark pulses where one is rationally shaped to induce temporal evolution of the transient excited population that is the inverse of the evolution induced by the other. The work is conducted in the weak-field regime with the sodium atom as the model system. The approach developed here is general, conceptually simple, and very effective.

We present and implement a new scheme for independent control of both the final and the transient population utilizing the symmetry properties of the system. By proper pulse shaping, utilizing the invariance of the two-photon absorption to specific phase transformations of the pulse, different time evolutions of the transient population are photo-induced for a given (fixed) final state population. The model system is the Na atom. The work is conducted in the weak-field regime for which the transient two-photon excitation is described by second-order perturbation theory. One most attractive case is the extended family of third-order chirp pulses which control the population build-up duration independently of the final population.

Weak-field coherent phase control of atomic non-resonant multiphoton excitation induced by shaped femtosecond pulses is studied theoretically in the single-cycle regime. The carrier-envelope phase (CEP) of the pulse, which in the multi-cycle regime does not play any control role, is shown here to be a new effective control parameter that its effect is highly sensitive to the spectral position of the ultrabroad spectrum. Rationally chosen position of the ultrabroadband spectrum coherently induces several groups of multiphoton transitions from the ground state to the excited state of the system: transitions involving only absorbed photons as well as Raman transitions involving both absorbed and emitted photons. The intra-group interference is controlled by the relative spectral phase of the different frequency components of the pulse, while the inter-group interference is controlled jointly by the CEP and the relative spectral phase. Specifically, non-resonant two- and three-photon excitation is studied in a simple model system within the perturbative frequency-domain framework. The developed intuition is then applied to weak-field multiphoton excitation of atomic cesium (Cs), where the simplified model is verified by non-perturbative numerical solution of the time-dependent Schrödinger equation. We expect this work to serve as a basis for a new line of femtosecond coherent control experiments.

Femtosecond coherent phase control of resonance mediated

(2+1)

three-photon absorption is studied both theoretically and experimentally. The regime is perturbative of third order. The photoexcitation coherently combines elements of both nonresonant and resonance-mediated multiphoton transitions. By proper simple pulse shaping the three-photon absorption in Na is effectively controlled experimentally, enhanced up to $\ensuremath{\sim}300%$ of the absorption induced by the transform-limited pulse. It is achieved by phase manipulating intra- and intergroup interferences involving two groups of three-photon excitation pathways: (i) on resonance and (ii) near resonance with the intermediate resonance state accessed by nonresonant two-photon transition.

We present and implement a new scheme for extended multichannel selective femtosecond coherent control based on symmetry properties of the excitation channels. Here, an atomic nonresonant two-photon absorption channel is coherently incorporated in a resonance-mediated (2+1) three-photon absorption channel. By proper pulse shaping, utilizing the invariance of the two-photon absorption to specific phase transformations of the pulse, the three-photon absorption is tuned independently over an order-of-magnitude yield range for any possible two-photon absorption yield. Noticeable is a set of "two-photon dark pulses" inducing widely tunable three-photon absorption.

We introduce a new scheme for generating short-wavelength coherent broadband radiation with well-controlled spectral characteristics. It is based on shaping long-wavelength femtosecond pulse to coherently control atomic resonance-mediated (2+1) three-photon excitation to a broad far-from-resonance continuum. Here, the spectrum (central frequency and bandwidth) of deep-ultraviolet coherent broadband radiation generated in Na vapor is experimentally controlled by tuning the linear chirp we apply to the driving phase-shaped near-infrared femtosecond pulse. This is a first step in implementing the full scheme for producing shaped femtosecond pulses at wavelengths down-to the vacuum-ultraviolet range.