We report the generation of squeezed vacuum states of light at 1550 nm with a broadband quantum noise reduction of up to 4.8 dB ranging from 5 MHz to 1.2 GHz sideband frequency. We used a custom-designed 2.6 mm long biconvex periodically-poled potassium titanyl phosphate (PPKTP) crystal. It featured reflectively coated end surfaces, 2.26 GHz of linewidth and generated the squeezing via optical ...

We analyze a new scheme for generating squeezed states in a short semiconductor AlxGa12xAs waveguide with x s3d nonlinearity at below half the band-gap energy. We find that for a Gaussian pulse the amount of squeezing achievable is limited by the squeezed-state detection phase mismatch caused by the pump selfphase modulation and is also degraded slightly by the pump–probe phase mismatch that is...

Squeezed states are characterized by a phasedependent redistribution of quantum fluctuations such that the dispersion in one of the two quadrature components of the field is reduced below the level set by the symmetric distribution of the vacuum state or a coherent state [1]. Such a property has been used to raise the sensitivity beyond the standard quantum limit [2, 3] and to enhance interfero...

We analyze squeezing of the nanoresonator state produced by periodic measurement of position by a quantum point contact or a single-electron transistor. The mechanism of squeezing is the stroboscopic quantum nondemolition measurement generalized to the case of continuous measurement by a weakly coupled detector. The magnitude of squeezing is calculated for the harmonic and stroboscopic modulati...

We consider the precise quantum state of two trapped, coupled Bose Einstein condensates in the two-mode approximation. We seek a representation of the state in terms of a Wigner-like distribution on the two-mode Bloch sphere. The problem is solved using a self-consistent rotation of the unknown state to the south pole of the sphere. The two-mode Hamiltonian is projected onto the harmonic oscill...

Quantum entanglement in the Hénon–Heiles system is analyzed using the squeezed coherent state. Enhancement of quantum entanglement via squeezing is explored in connection with chaotic and regular dynamics of the system. It is found that the entanglement enhancement via squeezing is implicitly linked to the local structure of the classical phase-space and it shows a clear quantum-classical corre...

We experimentally examine the nonclassical character of a class of non-Gaussian states known as phasediffused squeezed states. These states may show no squeezing effect at all and therefore provide an interesting example to test nonclassicality criteria. The characteristic function of the Glauber-Sudarshan representation P function proves to be a powerful tool to detect nonclassicality. Using t...

We investigate the dependence of spin squeezing on the polar angle of the initial coherent spin state |θ0, φ0〉 in a generalized one-axis twisting model, where the detuning δ is taken into account. We show explicitly that regardless of δ and φ0, previous results of the ideal one-axis twisting is recovered as long as θ0 = π/2. For a small departure of θ0 from π/2, however, the achievable variance...

Time-dependent linear coupling between macroscopic quantum resonator modes generates both a parametric amplification also known as a “squeezing operation” and a beam splitter operation, analogous to quantum optical systems. These operations, when applied properly, can robustly generate entanglement and squeezing for the quantum resonator modes. Here, we present such coupling schemes between a n...

In this paper, we investigate the effects of spin squeezing on two-coupled quantum kicked tops, which have been previously shown to exhibit a quantum signature of chaos in terms of entanglement dynamics. Our results show that initial spin squeezing can lead to an enhancement in both the entanglement rate and the asymptotic entanglement for kicked tops when the initial state resides in the regul...