Strongly squeezed light finds many important applications within the fields of quantum metrology, quantum communication and quantum computation. However, due to the bulkiness and complexity of most squeezed light sources of today, they are still not a standard tool in quantum optics labs. We have taken the first steps in realizing a compact, high-performance 1550 nm squeezing source based on commercially available fiber components combined with a free-space double-resonant parametric down-conversion source. The whole setup, including single-pass second-harmonic generation in a waveguide, fits on a 30 cm×45 cm breadboard and produces 9.3 dB of squeezing at a 5 MHz sideband-frequency. The setup is currently limited by phase noise, but further optimization and development should allow for a 19" sized turn-key squeezing source capable of delivering more than 10 dB of squeezing.
Strongly squeezed light finds many important applications within the fields of quantum metrology, quantum communication and quantum computation. However, due to the bulkiness and complexity of most squeezed light sources of today, they are still not a standard tool in quantum optics labs. We have taken the first steps in realizing a compact, high-performance 1550 nm squeezing source based on commercially available fiber components combined with a free-space double-resonant parametric down-conversion source. The whole setup, including single-pass second-harmonic generation in a waveguide, fits on a 30 cm×45 cm breadboard and produces 9.3 dB of squeezing at a 5 MHz sideband-frequency. The setup is currently limited by phase noise, but further optimization and development should allow for a 19" sized turn-key squeezing source capable of delivering more than 10 dB of squeezing.
Quantum-correlated states of light, such as squeezed states, constitute a fundamental resource for quantum technologies, enabling enhanced performance in quantum metrology, quantum information processing, and quantum communications. The practical deployment of such technologies requires squeezed-light sources that are compact, efficient, low-cost, and robust. Here we report a compact narrowband source of two-mode squeezed light at 795 nm based on four-wave mixing in hot 85Rb atomic vapor. The source is implemented in a small, modular architecture featuring a single fiber-coupled input, an electro-optic phase modulator combined with a single Fabry-Perot etalon for probe generation, and two free-space output modes corresponding to the signal and conjugate fields. Optimized for low pump power, the system achieves up to -8 dB of intensity-difference squeezing at an analysis frequency of 0.8 MHz with a pump power of only 300 mW. The intrinsic narrowband character of the generated quantum states makes this source particularly well suited for atomic-based quantum sensing and quantum networking, including interfaces with atomic quantum memories. Our results establish a versatile and portable platform for low-SWaP squeezed-light generation, paving the way toward deployable quantum-enhanced technologies.
Quantum correlated states of light, such as squeezed states, are a fundamental resource for the development of quantum technologies, as they are needed for applications in quantum metrology, quantum computation, and quantum communications. It is thus critical to develop compact, efficient, and robust sources to generate such states. Here, we report on a compact, narrowband, fiber-coupled source of two-mode squeezed states of light at 795 nm based on four-wave mixing (FWM) in an 85Rb atomic vapor. The source is designed in a small modular form factor, with two input fiber-coupled beams, the seed and pump beams required for the FWM, and two output fibers, one for each of the modes of the squeezed state. The system is optimized for low pump power (135 mW) to achieve a maximum intensity-difference squeezing of 4.4 dB after the output of fibers at an analysis frequency of 1 MHz. The narrowband nature of the source makes it ideal for atomic-based quantum sensing and quantum networking configurations that rely on atomic quantum memories. Such a source paves the way for a versatile and portable platform for applications in quantum information science.
Squeezed states of light were observed for the first time in 1985.Since then they have developed into an important nonclassical tool in the field of high-precision metrology, for instance in gravitational wave detection, as well as in the field of quantum information, e.g. for teleportation and quantum cryptography.For all these applications a strong squeezing factor is beneficial.This thesis presents a new benchmark value for squeezed light from non-monolithic squeezed-light sources.By means of parametric down-conversion, squeezed states at a wavelength of 1064 nm were generated and a nonclassical noise suppression of 12.3 dB was observed.In contrast to a monolithic resonator, the resonance frequency of this squeezed-light source can be adjusted to a downstream experiment.In an additional experiment this squeezed-light source was utilized to determine the quantum efficiency of photo diodes.The applied method permits high precision since strong squeezing is sensitive to even low values of optical loss.In view of the application of squeezed light in future-generation gravitational wave detectors and quantum information science, a dedicated squeezed-light source was developed and at a wavelength of 1550 nm squeezing in the continuous-wave regime was observed for the first time.These squeezed states were employed to quantumenhance the sensitivity of a fiber-based Sagnac interferometer.Thus the compatibility of squeezing at 1550 nm with fiber-based quantum communication was demonstrated.Furthermore, upon thorough optimization of the squeezed-light generation and detection at 1550 nm, a quantum noise suppression of 12.3 dB was measured.Moreover, squeezing in the Fourier audio-band was observed for the first time.The findings presented in this thesis constitute key research towards the squeezed-light technology at 1550 nm as it is required for future gravitational wave detectors such as the recently proposed Einstein Telescope.
Squeezed light is a fundamental nonclassical resource in quantum optics, and considerable progress has been made in its generation and manipulation. Here, we experimentally demonstrate a compact higher-order spatial modes squeezed light source, achieved by integrating second-harmonic generation and optical parametric oscillation within a single doubly resonant cavity. The HG 2 m ,2 n pump field, which is essential for the generation of HG m , n mode squeezed states, is produced via internal second-harmonic generation, substantially enhancing both the conversion efficiency and mode purity. With this configuration, we successfully generated squeezed vacuum states in the HG 0,0 , HG 1,0 , and HG 2,0 modes, achieving squeezing levels of −4.53 ± 0.26 dB, −3.68 ± 0.19 dB, and −2.58 ± 0.08 dB, respectively. This platform provides a viable pathway for scalable, multimode quantum state generation, with broad potential in quantum metrology and quantum communication.
The squeezed states of light become more and more important in the fields of quantum enhanced precision measurement and quantum information. To get this vital continuous variable quantum resource, the generation of squeezed states of light becomes a key factor. In this paper, a compact telecom fiber-based bright squeezed light (BSL) generator is demonstrated. To our knowledge, this is the first time that BSL has been reported in a fiber-based system to date. To obtain the BSL, a double-pass parametric amplifier based on surface-coated lithium niobate waveguide is employed. When the 1550 nm seed laser of the parametric amplifier is blocked, a stable 1.85 dB squeezed vacuum is obtained. With injected seed power of 80 μW, an output power of 18 μW and a squeezing value of 1.04 dB are achieved of the BSL at 1550 nm. Due to the good mode matching in the fiber and the absence of the resonant cavity, this flexible and compact BSL generator has the potential to be useful in out-of-the-laboratory quantum technologies. Moreover, the BSL has a narrow spectral width of 30 kHz, which is inherited from a narrow-linewidth single-frequency seed laser. In addition to being free from the wavelength-dependent losses, the narrowband BSL is also beneficial to improve the signal-to-noise ratio of quantum-enhanced precision measurement.
Lasers for generating monochromatic light beams with sideband spectra in strongly squeezed vacuum states are the basis for aspired optical continuous-variable quantum computers. We have developed a "squeeze laser" that produces 10 dB squeezed vacuum states at a wavelength of 1550 nm, the latter being tunable by 0.5 nm without losing the high squeeze factor. Several identical squeeze lasers can thus be combined to realise wavelength-division multiplexing. Our squeeze laser uses the mature technology of parametric down-conversion in a periodically poled KTP crystal placed in a cavity that resonates both the squeezed field and the second harmonic pump field. Unlike previous realisations, we achieve the double resonance and phase matching by individually optimising and controlling the temperatures of two sections of the crystal body. The wavelength range is currently limited by the tuneability of the 1550 nm master laser.