Using a few-cycle femtosecond pulse with tailored group delay dispersion as the pump of a parametric down-conversion process, we produce bright entangled light pulses with more than 80% occupancy of a single temporal mode and a duration shorter than 4 optical cycles at near-infrared frequencies. Such states promise to open new opportunities in quantum metrology, such as subcycle sampling of mid-infrared quantum fields.
Using a few-cycle femtosecond pulse with tailored group delay dispersion as the pump of a parametric down-conversion process, we produce bright entangled light pulses with more than 80% occupancy of a single temporal mode and a duration shorter than 4 optical cycles at near-infrared frequencies. Such states promise to open new opportunities in quantum metrology, such as subcycle sampling of mid-infrared quantum fields.
We introduce an ultrafast, bright, entangled twin-beam source generated by type-0 parametric down-conversion in periodically-poled lithium niobate at MHz repetition rate, with continuously tunable Schmidt number K set by the pump pulse duration. Photon-number statistics characterization via g(2)(0) and singular-value decomposition of the signal spectral density matrix yield K≃1.05 and K≃1.03, respectively, maintained over multiple orders of magnitude in brightness. Group-delay dispersion of the pump drives a continuous transition from single-mode operation to a controlled multimode regime, consistent with the temporal gain window departing from the inverse phase-matching bandwidth. Strong non-degeneracy of the source (signal at 1.37 um, idler at 4.0 um, ∼100 fs duration) decouples a mid-infrared interaction wavelength, which overlaps with molecular vibrational resonances, from a near-infrared detection band, establishing a practical platform for quantum-enhanced metrology, nonlinear interferometry, and mid-infrared spectroscopic sensing. We show that in the bright few-mode limit, the total entanglement resource is clearly separated between modal and occupational degrees of freedom, and that our source allocates up to 95-97% of that resource to the occupational sector.
We introduce an ultrafast, bright, entangled twin-beam source generated by type-0 parametric down-conversion in periodically-poled lithium niobate at MHz repetition rate, with continuously tunable Schmidt number K set by the pump pulse duration. Photon-number statistics characterization via g(2)(0) and singular-value decomposition of the signal spectral density matrix yield K ~ 1.05 and K ~ 1.03, respectively, maintained over multiple orders of magnitude in brightness. Group-delay dispersion of the pump drives a continuous transition from single-mode operation to a controlled multimode regime, consistent with the temporal gain window departing from the inverse phase-matching bandwidth. Strong non-degeneracy of the source (signal at 1.37 µm, idler at 4.0 µm, ~ 100 fs duration) decouples a mid-infrared interaction wavelength, which overlaps with molecular vibrational resonances, from a near-infrared detection band, establishing a practical platform for quantum-enhanced metrology, nonlinear interferometry, and mid-infrared spectroscopic sensing. We show that in the bright few-mode limit, the total entanglement resource is clearly separated between modal and occupational degrees of freedom, and that our source allocates up to 95-97% of that resource to the occupational sector.
We introduce an ultrafast, bright, entangled twin-beam source generated by type-0 parametric down-conversion in periodically-poled lithium niobate at MHz repetition rate, with continuously tunable Schmidt number K set by the pump pulse duration. Photon-number statistics characterization via g(2)(0) and singular-value decomposition of the signal spectral density matrix yield K ~ 1.05 and K ~ 1.03, respectively, maintained over multiple orders of magnitude in brightness. Group-delay dispersion of the pump drives a continuous transition from single-mode operation to a controlled multimode regime, consistent with the temporal gain window departing from the inverse phase-matching bandwidth. Strong non-degeneracy of the source (signal at 1.37 µm, idler at 4.0 µm, ~ 100 fs duration) decouples a mid-infrared interaction wavelength, which overlaps with molecular vibrational resonances, from a near-infrared detection band, establishing a practical platform for quantum-enhanced metrology, nonlinear interferometry, and mid-infrared spectroscopic sensing. We show that in the bright few-mode limit, the total entanglement resource is clearly separated between modal and occupational degrees of freedom, and that our source allocates up to 95-97% of that resource to the occupational sector.
In quantum optics, quantization of the electromagnetic field typically occurs in a finite volume - a cavity - which results in discrete frequency modes where photons are created, annihilated and exchanged between such modes. As a result, evolution of quantum optical states is periodic in the carrier wave of the field, measurement protocols return cycle-averaged information, and any sub-cycle evolution that is foundational to many light-matter interactions, especially at high field strengths, remains hidden. Adapting an attosecond technique, here we capture the electric-field evolution of a quantum optical state, femtosecond bright squeezed vacuum, with sub-cycle precision. We find that it consists of many stochastic, time-localized bursts within each pump pulse whose phase randomly switches between two values. We exploit the random phase flips to generate quantum random bit sequences with a generation rate that can reach petahertz frequencies. In addition, the sub-cycle resolution allows us to measure coherence functions of the waveforms between any two times, which we explain with a superposition of time-limited modes. These results bridge attosecond metrology and quantum optics and pave the way to measuring quantum light-matter interactions as they evolve on a few-femtosecond time scale, and integrate quantum randomness in petahertz electronics.
Following a general introduction to the nonlinear optical process of spontaneous parametric downconversion, in this talk, we will review recent progress made on the generation and characterization of bright ultrafast quantum light, including bright squeezed vacuum and correlated two-pulse emission (bright twin beams). Such properties as 10^6-10^13 average photon number per pulse, few-cycle duration and more are proving advantageous for enabling novel quantum nonlinear optical applications, which we will briefly review in the concluding part of the talk.