Phase Squeezing Research Articles

Fractality-induced topological phase squeezing and devil's staircase

Fractality-induced topological phase squeezing and devil's staircase

High-precision multiparameter estimation of mechanical force by quantum optomechanics.

A nanomechanical oscillator can be used as a sensitive probe of a small linearized mechanical force. We propose a simple quantum optomechanical scheme using a coherent light mode in the cavity and weak short-pulsed light-matter interactions. Our main result is that if we transfer some displacement to the mechanical mode in an initialization phase, then a much weaker optomechanical interaction is enough to obtain a high-precision multiparameter estimation of the unknown force. This approach includes not only estimating the displacement caused by the force but also simultaneously observing the phase shift and squeezing of the mechanical mode. We show that the proposed scheme is robust against typical experimental imperfections and demonstrate the feasibility of our scheme using orders of magnitude weaker optomechanical interactions than in previous related works. Thus, we present a simple, robust estimation scheme requiring only very weak light-matter interactions, which could open the way to new nanomechanical sensors.

Phase squeezing of quantum hypergraph states

Corresponding to a hypergraph G with d vertices, a quantum hypergraph state is defined by , where f is a d-variable Boolean function depending on the hypergraph G, and denotes a binary vector of length 2 d with 1 at the nth position for n = 0, 1, …(2 d − 1). The nonclassical properties of these states are studied. We consider the annihilation and creation operator on the Hilbert space of dimension 2 d acting on the number states . The Hermitian number and phase operators, in finite dimensions, are constructed. The number-phase uncertainty for these states leads to the idea of phase squeezing. We establish that these states are squeezed in the phase quadrature only and satisfy the Agarwal–Tara criterion for nonclassicality, which only depends on the number of vertices of the hypergraphs. We also point out that coherence is observed in the phase quadrature.

Nonclassical atomic system dynamics time-dependently interacts with finite entangled pair coherent parametric converter cavity fields

We consider a time-dependent model that describes a qubit time-dependently interacting with a cavity containing finite entangled pair coherent parametric converter fields. The dynamics of some quantum phenomena, as: phase space information, quantum entanglement and squeezing, are explored by atomic Husimi function, atomic Wehrl entropy, variance, and entropy squeezing. The influences of the unitary qubit-cavity interaction, the difference between the two-mode photon numbers, the initial atomic coherence, and the time-dependent qubit location are investigated. It is found that the regularity, the amplitudes and the frequency of the quantum phenomena can be controlled by the physical parameters. For the initial atomic pure state, the qubit-cavity entanglement, the qubit phase space information, and atomic squeezing can be generated strongly compared to those of the initial atomic mixed state. The time-dependent location parameters enhance the generated quantum phenomena, and their effect can be enhanced by the parameters of the two-mode photon numbers and the initial atomic coherence.

All-optical phase regeneration for DP-QPSK/8PSK signals based on dual-conjugate pump degenerate phase sensitive amplification

An all-optical phase regeneration scheme for advanced modulated signals is proposed using dual-conjugate pump degenerate phase sensitive amplification. By engineered placement of the pump and signal wavelengths as well as the reduction of required conjugate harmonics’ order, viable phase squeezing of up to eighth-order is achieved. Feasibility of the scheme is verified through theoretical analysis and simulations. Key parameters such as signal-to-idler power ratio are investigated to optimize the phase regeneration performance. Combined with a subsequent phase-preserving amplitude regenerating device, the overall error vector magnitude decreases of regenerated DP-QPSK and DP-8PSK signals are about from 19% to 3% and from 9%. Furthermore, optical signal noise ratio improvements of 1.9 dB and 2.1 dB are achieved for phase noise of 20 degrees and 10 degrees, respectively. This shows the potential of the scheme to recover dual polarization signals’ quality and prolong transmission reach.

Fermionic versus bosonic two-site Hubbard models with a pair of interacting cold atoms

In a recent work, Murmann et al (2015 Phys. Rev. Lett. 114 080402) have experimentally prepared and manipulated a double-well optical potential containing a pair of Fermi atoms as a possible building block of Hubbard model. Here, we carry out a detailed theoretical study on the properties of both fermionic and bosonic two-site Hubbard models with a pair of interacting atoms in a trap with a double-well structure along z-axis and a 2D harmonic confinement along the transverse directions. We consider fermions as of two-component type and bosons as of spinless as well as of two spin components. We first calculate Hubbard parameters using the finite-range interaction potentials of Jost and Kohn. In general, a finite range of interaction leads to on-site, inter-site, exchange and partial-exchange terms We show that, given the same input parameters for both bosonic and fermionic two-site Hubbard models, many of the statistical properties such as the single- and double-occupancy of a site, and the probabilities for the single-particle and pair tunneling are similar in both fermionic and bosonic cases. But, quantum entanglement and quantum fluctuations are found to be markedly different for the two cases. We discuss atom-atom entanglement in two spatial modes corresponding to the two sites of the double-well. Our results show that the entanglement of a pair of spin-half fermions is always greater than that of spinless bosons; and when the fermions are maximally entangled the fluctuation in the two-mode phase difference is largely squeezed. In contrast, spinless bosons never exhibit phase squeezing, but shows squeezing in two-mode population imbalance depending on the system parameters.

Directional steering as a sufficient and necessary condition for Gaussian entanglement swapping: Application to distant optomechanical oscillators

Einstein-Podolsky-Rosen (EPR) steering is a quantum nonlocal effect that characterizes the ability to remotely control quantum states of one system via local measurements on another distant system entangled with the controlled one. Entanglement swapping is an effective way to realize distant entanglement, which is useful for building quantum networks. Previous studies show that the presence of entanglement of subsystems in mixed states is merely necessary for achieving entanglement swapping. In this paper, we find that for Gaussian entanglement swapping with two pairs of entangled modes ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{j}$ and ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{b}}_{j}\phantom{\rule{4pt}{0ex}}(j=1,2)$, the existence of directional EPR steering from the modes ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{b}}_{j}$ under homodyne detection to the other modes ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{j}$ is a sufficient and necessary condition for achieving swapped entanglement between modes ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{1}$ and ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{2}$, and moreover this achievement is independent of the reverse steering from modes ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{j}$ to ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{b}}_{j}$. We further reveal that this is because the steering in that direction enables the amplitude and phase squeezing of the two composite modes of modes ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{1}$ and ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{2}$ via homodyne detection, which is necessary and sufficient for swapped entanglement. As a concrete example, we next investigate light-mechanical steering in a dispersively or dissipatively coupled optomechanical system, and we consider the generation of entanglement between two distant optomechanical oscillators via entanglement swapping by utilizing steering. It is interesting to find that even without the constraint that the cavity linewidth should be smaller than the mechanical frequency, robust mechanical entanglement can be obtained in the steady-state regime.

Quadrature-squeezed light and optomechanical entanglement in a dissipative optomechanical system with a mechanical parametric drive

We propose a scheme for producing the phase squeezing of the output light in a dissipative optomechanical coupling system. This is achieved by applying a degenerate parametric drive on the mechanical oscillator. We also show that this scheme is capable of generating the stationary entanglement between an optical cavity field and a macroscopic mechanical oscillator. The effects of the strength of the mechanical parametric drive, the power of the input laser, the temperature of the environment on the output phase squeezing, and the optomechanical entanglement are investigated. For a temperature of 20 mK, we find that up to 9 dB of the output phase squeezing and the large optomechanical entanglement can be achieved.

Atomic Phase Space Entropy, Squeezing and Purification Properties of a Two Coupled Superconducting Qubits in Solid State Systems

Atomic Phase Space Entropy, Squeezing and Purification Properties of a Two Coupled Superconducting Qubits in Solid State Systems

Generation of squeezed vacuum on cesium D2 line down to kilohertz range**Project supported by the National Natural Science Foundation of China (Grant Nos. 11634008, 61227902, 11574187, and 11674203), the National Key Research and Development Program of China (Grant No. 2017YFA0304500), and the Fund of “1331 Project” Key Subjects Construction of Shanxi Province, China.

We report the experimental generation of a squeezed vacuum at frequencies ranging from 2.5 kHz to 200 kHz that is resonant on the cesium D2 line by using a below-threshold optical parametric oscillator (OPO). The OPO is based on a periodically-poled KTiOPO4 (PPKTP) crystal that is pumped using a bow-tie four-mirror ring frequency doubler. The phase of the squeezed light is controlled using a quantum noise locking technique. At a pump power of 115 mW, maximum quadrature phase squeezing of 3.5 dB and anti-squeezing of 7.5 dB are detected using a home-made balanced homodyne detector. This squeezed vacuum at an atomic transition in the kilohertz range is an ideal quantum source for quantum metrology of enhancing measurement precision, especially for ultra-sensitive measurement of weak magnetic fields when using a Cs atomic magnetometer in the audio frequency range.

The Effect of Wound Incision Care Using Honey and Povidone Iodine 10%

Introduction : Povidoe iodine often used in incision treatment. This study was aimed to explain the differences between honey and povidone iodine 10% on incision healing, were unknown.Method : This study used a true experiment design with 18 samples of 3 years old-male guinea pigs, divided into three groups. One-control group and 2 treatment groups. This classification was done randomize. The independent variable was used of honey and 10-% povidon iodin and the dependent variable was inflammation phase (squeezing, edema, plasma of incision) and proliferation (granulation, incision edge unification, skin structure) were assessed in the third and sixth days. Data were collected by using observation of the signs both of inflammation and proliferation phase and analyzed using Chi Square with level of significance α ≤ 0.05.Result : Results showed that there was no significant difference in the third and sixth days inflammation. In contrast, a significant difference was obtained in the third and sixth days proliferation. Granulation (p< 0,05), incision edge unification (p< 0,05), establishment of skin structures (p< 0,05).Conclusion: It can be concluded that the honey usage was proven to be more effective in accelerated incision healing, increasing proliferation and reduce any infection risks. For future research there is neeed to conduct a microscopically observation of numerous changes in collagen, PMN-cell (neutrophile) and MN-cell (lymphocyte and monocyte), inflammation and proliferation as well as incision healing process.

Digital optical processing of optical communications: towards an Optical Turing Machine

AbstractOptical computing is needed to support Tb/s in-network processing in a way that unifies communication and computation using a single data representation that supports in-transit network packet processing, security, and big data filtering. Support for optical computation of this sort requires leveraging the native properties of optical wave mixing to enable computation and switching for programmability. As a consequence, data must be encoded digitally as phase (M-PSK), semantics-preserving regeneration is the key to high-order computation, and data processing at Tb/s rates requires mixing. Experiments have demonstrated viable approaches to phase squeezing and power restoration. This work led our team to develop the first serial, optical Internet hop-count decrement, and to design and simulate optical circuits for calculating the Internet checksum and multiplexing Internet packets. The current exploration focuses on limited-lookback computational models to reduce the need for permanent storage and hybrid nanophotonic circuits that combine phase-aligned comb sources, non-linear mixing, and switching on the same substrate to avoid the macroscopic effects that hamper benchtop prototypes.

The theoretical investigation of the impact of two-photon absorption and free-carrier absorption on phase-sensitive amplification in silicon waveguides

We investigate the influence of two-photon absorption (TPA) and free-carrier absorption (FCA) on phase-sensitive amplification (PSA) process in a dispersion engineered silicon strip waveguide at the telecom wavelengths. The phase-dependent gain and phase-to-phase transfer functions as well as the phase regeneration capacity of PSA are numerically analysed. It is found that TPA and FCA will suppress the phase-sensitive extinction ratio (PER) and the efficiency of phase squeezing. Moreover, the phase regeneration capability of silicon waveguide-based PSA is investigated by comparing the regenerated signal waveforms at a different signal power with/without TPA and FCA. Our results have potential application in all-optical signal regeneration.

Total Phase and Light Squeezing for a Two-Level System in a New Nonlinear Coherent State

The total phase and squeezing properties of light are important features in performing different tasks in quantum information processing such as quantum cryptography and teleportation. These quantum information tasks depend on finding the states in which squeezing in entropy can be created. In this paper, we investigate the entropy squeezing and total phase for a two-level system interacting with nonlinear coherent state (NCS). We explore the link between the total phase and squeezing properties of information entropy. We examine the influence of the atomic motion and the intensity-dependent function on the dynamics of the entropy squeezing and total phase. We show that there is a kind of correlation between the total phase and the entropy squeezing for stationary and moving atoms.

Nonclassicality of New Class of States Produced by Superposition of Two Nonlinear Squeezed States with Respective Phase φ

In this paper, we consider two classes of nonlinear squeezed states: squeezed vacuum and squeezed one-photon states, which according to their generation processes, essentially include respectively even and odd bases of Fock space. Then, we produce their general superposition with respective phase φ which consists of all bases of Fock space. As a physical realization of the presented approach, we will use the q -deformation nonlinearity function to produce the corresponding nonlinear squeezed states and their superposition. In the continuation, due to extensive interest in nonclassicality features, we discuss about their main nonclassical properties such as sub-Poissonian statistics, normal and amplitude squared squeezing, number and phase squeezing and Husimi quasi-probability function of the obtained states and compare with those of the original constituent components. Meanwhile, we also pay attention to linear squeezed states (vacuum and one-photon) and particularly their superposition, too. Accordingly, the nonclassicality features of the introduced states are evidently established. At last, simple schemes for the generation of such states are presented.

Phase squeezing and dispersion tolerance of phase sensitive amplifier using periodically poled LiNbO_3 waveguide

The phase squeezing property of phase sensitive amplifiers (PSAs) is a useful feature to recover signal quality. Chromatic dispersion of transmission fiber largely affects the performance of PSAs when they are used as in-line amplifiers in long-haul transmission systems. In this work, we demonstrated that phase variation such as chirping can be reduced by phase squeezing in a periodically poled LiNbO3 (PPLN)-based PSA. We also examined the dispersion tolerance of a PPLN-based in-line PSA. Theoretical analysis and experiment revealed that we can relay the received data with negligible power penalty utilizing the phase squeezing capability of the PSA, if the phase variation due to dispersion within the data bandwidth is below π/2.

In-line phase-sensitive amplification of QPSK signal using multiple quasi-phase matched LiNbO₃ waveguide.

Phase-sensitive amplifiers (PSA) using periodically poled (PPLN) LiNbO₃ waveguides are promising as low-noise optical amplifiers. However, it is difficult to realize in-line operation for multi-level phase modulated signals using a PPLN based PSA with the conventional configuration. In this paper, we report a PPLN based in-line PSA that can regenerate quadrature phase shift keying (QPSK) signals. Multi-stage frequency mixing in a multiple quasi-phase matched LiNbO₃waveguide allows carrier phase recovery from a QPSK signal. Non-degenerate parametric amplification enables the phase-sensitive amplification of a QPSK signal. Amplitude and phase regeneration is examined utilizing gain saturation and phase squeezing capability.

Numerical Investigation of the Geometric Phase and Entropy Squeezing for a Two-Level System in the Presence of Decoherence Terms

In this paper, we have presented the numerical investigation of the geometric phase and field entropy squeezing for a two-level system interacting with coherent field under decoherence effect during the time evolution. The effects of the initial state setting and atomic dissipation damping parameter on the evolution of the geometric phase and entropy squeezing have been examined. We have reported some new results related to the periodicity and regularity of geometric phase and entropy squeezing.

Investigation of an All-Optical Black-Box PPLN-PPLN BPSK Phase Regenerator

We investigate the phase squeezing performance of an all-optical black-box binary phase-shift keyed phase regenerator constructed from periodically-poled lithium-niobate (PPLN) waveguides. Phase regeneration is performed with different levels of phase noise and constant amplitude noise added to the phase modulated input. We experimentally show that, for moderate phase noise, unwanted phase-to-amplitude noise conversion can be minimized without degradation of the phase squeezing performance, by controlling the signal-to-pump power ratio at the input to the PPLN-based phase-sensitive regenerator.

Nonlinear semi-coherent states, their nonclassical features and phase properties

Semi-coherent states (semi-CSs) were previously introduced and their nonclassical properties studied. In this paper, we first propose a general formalism for the construction of ‘nonlinear semi-CSs’ as an extension of semi-CSs and then their explicit form in the number state basis is generally deduced. Next, as some physical appearances of the formalism, after choosing two well-known nonlinearity functions, nonclassical features and quantum statistical properties of the associated states are studied by evaluating quadrature squeezing, higher order squeezing and the Mandel parameter, as well as their phase properties and number and phase squeezing of the introduced states. Finally, the results are compared with the properties of semi-CSs.