This thesis presents the first experimental demonstration of two-dimensional spatial squeezing. A dual squeezer was used to produce two beams of temporally squeezed light. Specially designed wave-plates were required to generate the necessary spatially orthogonal modes. These modes were mixed on an optical cavity to form a multi-mode superposition that converted the original temporal correlations into the desired spatial correlations. We used this light to improve the sensitivity of a two-dimensional beam displacement measurement to below the quantum noise limit. Our setup was also configured to generate a one-dimensional spatially squeezed state of light that did not require either of the two input modes to suffer substantial loss. This was the first experimental demonstration of a proper spatial squeezing measurement.
This thesis presents the first experimental demonstration of two-dimensional spatial squeezing. A dual squeezer was used to produce two beams of temporally squeezed light. Specially designed wave-plates were required to generate the necessary spatially orthogonal modes. These modes were mixed on an optical cavity to form a multi-mode superposition that converted the original temporal correlations into the desired spatial correlations. We used this light to improve the sensitivity of a two-dimensional beam displacement measurement to below the quantum noise limit. Our setup was also configured to generate a one-dimensional spatially squeezed state of light that did not require either of the two input modes to suffer substantial loss. This was the first experimental demonstration of a proper spatial squeezing measurement.
In this thesis we study three aspects of squeezed light. First, we investigate the generation of pulsed, near‑pure, degenerate, single‑temporal‑mode squeezed light produced by dual‑pump spontaneous four wave mixing in integrated silicon‑nitride coupled‑ring resonators. We show that parasitic spontaneous four wave mixing processes inherent to the dual‑pump configuration can substantially degrade the amount of generated squeezing and state purity. To mitigate these effects we explore pump detuning, engineered dispersion, and an auxiliary‑ring structure as suppression strategies. We then optimize the incident pump amplitude and phase, demonstrating that longer pump pulses can yield highly squeezed, temporally separable states and that an appropriate pre‑chirp tracks the effects of self‑ and cross‑phase modulation, increasing intracavity pump amplitudes and the amount of generated squeezing. Next, we analyze the spectral–temporal structure and photon statistics of strongly correlated squeezed light. We develop a general formalism based on the Whittaker–Shannon interpolation of the joint‑temporal amplitude that is particularly useful in the long‑pulse and continuous‑wave limits, where the instantaneous photon density is low but the total photon number may be large. This packet‑based description provides a local, physically transparent account of the state and its photon statistics that complements the Schmidt decomposition, and extends to nonclassical states for which a Schmidt decomposition is not available. Finally, we examine whether or not squeezed illumination can enhance two‑photon excitation relative to classical light, and whether any enhancement is experimentally detectable. We construct a model including radiative and nonradiative broadening to compute scattered and absorbed energy, and apply it to fluorescence from cesium atoms in a magneto‑optical trap driven by classical and squeezed light in both continuous‑wave and pulsed regimes. Under ideal conditions squeezed light can produce a measurable enhancement in both limits, but the gains are moderate and smaller than some recent molecular reports; additional broadening or loss would further reduce detectability.
As the generation of squeezed states of light has become a standard technique in laboratories, attention is increasingly directed towards adapting the optical parameters of squeezed beams to the specific requirements of individual applications. It is known that imaging, metrology, and quantum information may benefit from using squeezed light with a tailored transverse spatial mode. However, experiments have so far been limited to generating only a few squeezed spatial modes within a given setup. Here, we present the generation of single-mode squeezing in Laguerre-Gauss and Bessel-Gauss modes, as well as an arbitrary intensity pattern, all from a single setup using a spatial light modulator (SLM). The degree of squeezing obtained is limited mainly by the initial squeezing and diffractive losses introduced by the SLM, while no excess noise from the SLM is detectable at the measured sideband. The experiment illustrates the single-mode concept in quantum optics and demonstrates the viability of current SLMs as flexible tools for the spatial reshaping of squeezed light.
As the generation of squeezed states of light has become a standard technique in laboratories, attention is increasingly directed towards adapting the optical parameters of squeezed beams to the specific requirements of individual applications. It is known that imaging, metrology, and quantum information may benefit from using squeezed light with a tailored transverse spatial mode. However, experiments have so far been limited to generating only a few squeezed spatial modes within a given setup. Here, we present the generation of single-mode squeezing in Laguerre-Gauss and Bessel-Gauss modes, as well as an arbitrary intensity pattern, all from a single setup using a spatial light modulator (SLM). The degree of squeezing obtained is limited mainly by the initial squeezing and diffractive losses introduced by the SLM, while no excess noise from the SLM is detectable at the measured sideband. The experiment illustrates the single-mode concept in quantum optics and demonstrates the viability of current SLMs as flexible tools for the spatial reshaping of squeezed light. (C) 2016 Optical Society of America
The measurement sensitivity of the pointing direction of a laser beam is ultimately limited by the quantum nature of light. To reduce this limit, we have experimentally produced a quantum laser pointer, a beam of light whose direction is measured with a precision greater than that possible for a usual laser beam. The laser pointer is generated by combining three different beams in three orthogonal transverse modes, two of them in a squeezed-vacuum state and one in an intense coherent field. The result provides a demonstration of multichannel spatial squeezing, along with its application to the improvement of beam positioning sensitivity and, more generally, to imaging.
Optical entanglement is a key requirement for many quantum communication protocols. Conventionally entanglement is formed between two distinct beams, with the quantum correlations being measured at separate locations. We show entanglement between the modes within one beam. Our technique is particularly elegant and a major advance towards practical systems with minimum complexity. We demonstrate three major experimental achievements: (i) only one source is required to produce squeezed light in two orthogonal spatial modes, (ii) the entanglement is formed through lenses and beam rotation, without the need of a beam splitter and (iii) the quantum correlations are measured directly and simultaneously using a multi pixel, quadrant detector.