Quantum Fisher Information of Entangled Coherent States in a Lossy Mach–Zehnder Interferometer

We give an analytical result for the quantum Fisher information of entangled coherent states in a lossy Mach-Zehnder interferometer recently proposed by Joo et al., [Phys. Rev. Lett. 107 （2011） 083601]. For small loss of photons, we find that the entangled coherent state can surpass the Heisenberg limit. Phrthermore, the formalism developed here is applicable to the study of phase sensitivity of multipartite entangled coherent states.     

Study of all-fiber asymmetric interleaver based on two-stage cascaded Mach–Zehnder Interferometer

In order to improve the transmission efficiency of optical-fiber communication system with 10 Gb/s + 40 Gb/s, an all-fiber interleaver with unequal passband is proposed and discussed, which is based on a two-stage cascaded Mach-Zehnder interferometer (MZI). The optimum value of structural parameters, such as splitting ratios of the couplers and the physical length differences of the interferometer arms, were chosen. One set of optimized data is validated in the experimental result. The experimental results and the theoretic analysis indicate that an all-fiber optical interleaver with 3 dB passband width in odd channels and even channels could be obtained, which having more than 60 GHz passband and 30 GHz passband, for transmission speed of 40 Gb/s and 10 Gb/s, respectively. By assigning different portions of spectrum to the 10 Gb/s and the 40 Gb/s channels, the bandwidth efficiency requirement of the 40 Gb/s channel is relieved, and therefore longer transmission distance can be achieved.     

Photonic Electric-Field Sensor Utilizing an Asymmetric Ti:LiNbO3 Mach–Zehnder Interferometer with a Dipole Antenna

Abstract

The use of an asymmetric Ti:LiNbO₃ Mach–Zehnder interferometer with a dipole antenna to measure an electric-field strength is described in this article. The device has a small size of 46 × 7 × 1 mm and operates at a wavelength of 1.3 μm. The AC output characteristics show the modulation depth of ~75% at V_π voltage of ~5.3 V. The minimum detectable electric fields are ~0.28 V/m and ~0.646 V/m, corresponding to a dynamic range of about ~32 dB and ~26 dB at frequencies 20 MHz and 50 MHz, respectively. The sensors exhibit an almost linear response for the applied electric-field intensity from 0.298 V/m to 29.84 V/m.     

Method for measuring waveguide propagation losses by means of a Mach–Zehnder Interferometer structure

In this paper, a method for measuring waveguide propagation losses by means of a Mach–Zehnder Interferometer (MZI) structure is reported. The method, based on the analysis of the transmission spectra of asymmetric MZIs, enables the propagation losses of the optical waveguides to be calculated without the requirement of identical coupling conditions for each measurement. In addition, the power imbalance of the branching structure in the MZI can also be obtained. Our theoretical analysis is supported by experimental measurements.     

Polymeric Multimode Interference Mach–Zehnder Interferometer Electro-Optic Switch Using Embedded Coplanar Waveguide Electrode: Theory,Design, and Analysis

Abstract

The self-imaging theory is improved for designing a polymer multimode interference Mach–Zehnder interferometer electro-optic switch. The electro-optic overlap factor is enhanced from 0.6510 to 0.9658 through adopting an embedded coplanar waveguide electrode. Considering the mode dispersion effect, formulations of time-domain response are derived, and switching characteristics are analyzed. The total device length is about 7.175 mm, the switching voltage is 2.622 V, and the switching time is 29.90 ps. The lightwave 3-dB bandwidth is 20 nm, the insertion loss is less than 2.70 dB, and the crosstalk under cross and bar states are less than ?55 dB and ?45 dB, respectively.     

Enhanced Phase Estimation in Parity-Detection-Based Mach–Zehnder Interferometer using Non-Gaussian Two-Mode Squeezed Thermal Input State

While the quantum metrological advantages of performing non-Gaussian operations on two-mode squeezed vacuum (TMSV) states have been extensively explored, similar studies in the context of two-mode squeezed thermal (TMST) states are severely lacking. This paper explores the potential advantages of performing non-Gaussian operations on TMST state for phase estimation using parity detection-based Mach–Zehnder interferometry and compares it with the TMSV case. To this end, a realistic photon subtraction, addition, and catalysis model is considered. A unified Wigner function of the photon subtracted, photon added, and photon catalyzed TMST state is derived, which is used to obtain the expression for the phase sensitivity. The results show that performing non-Gaussian operations on TMST states can enhance the phase sensitivity for significant squeezing and transmissivity parameter ranges. Because of the probabilistic nature of these operations, it is of utmost importance to consider their success probability. When the success probability is considered, the photon catalysis operation performed using a high transmissivity beam splitter is the optimal non-Gaussian operation. This contrasts with the TMSV case, where photon addition is observed as the most optimal. Further, the derived Wigner function of the non-Gaussian TMST states will be useful for state characterization and various quantum protocols.     

A Novel Mach–Zehnder Interferometer Based on Hybrid Liquid Crystal–Photonic Crystal Fiber

We propose a novel all fiber Mach–Zehnder interferometer(MZI) based on photonic crystal fiber(PCF) filled with liquid crystal(LC). The interference between the core mode and the cladding modes of a PCF is utilized.To excite the cladding modes, a region is formed using fiber fusion splicer. Due to the fact that varying effective index difference between the core region and the LC-filled cladding region can cause different transmission spectra,we mainly study the MZIs with different LC-filled structures and different lengths of LC filling. The measured results demonstrate that quite clear interference spectra can be obtained. Through analysis spatial frequency spectrum and temperature spectrum of two MZIs with different LC-filled structures, we can obtain that the MZI with adjacent two LC-filled holes has clearer interference spectrum and higher temperature sensitivity. Thus we choose this MZI to measure the temperature sensitivity with different lengths of LC filling. When the length of LC filling is 2 cm, the temperature sensitivities can be enlarged to 1.59 nm/C. The interferometer shows a good temperature tunability and sensitivity, which can be a good candidate for a highly tunable optical filtering and temperature sensing applications.     

Spectra in nested Mach–Zehnder interferometer experiments

By the means of the standard quantum mechanics formalism I present an explicit derivation of the structure of power spectra in Danan et al. and Zhou et al. experiments with nested dynamically changing Mach–Zehnder interferometers. The analysis confirms that we observe prominent, first-order peaks on frequencies related to some of the elements of the interferometer, but not on others. However, as I shall demonstrate, there are also other, weaker effects related to all relevant elements of the setup. In case of the Danan et al. setup, there are even peaks at all frequencies of element oscillations. When confronted in an experiment, these observations shall challenge the interpretation of the experiments based on anomalous trajectories of light.     

Some theoretical and experimental aspects of three-grating Mach–Zehnder atom interferometers

In this contribution, we present some recent theoretical results concerning the fringe contrast in Mach–Zehnder atom interferometers and the use of Bloch states to describe atomic diffraction. We also describe the observation of diffraction of lithium at thermal energy by a quasi-resonant laser standing wave.     

Phase precision of Mach–Zehnder interferometer in PM2.5 air pollution

This paper theoretically explores the effect of PM2.5 air pollution on the phase precision of a Mach–Zehnder interferometer. With the increasing of PM2.5 concentration, phase precision for inputs of coherent state vacuum state and inputs of coherent state squeezed vacuum state will gradually decrease and be lower than the standard quantum limit.When the value of relative humidity is increasing, the precision of two input cases is decreasing much faster. We also find that the precision for inputs of coherent state squeezed state is better than that of coherent state vacuum state when PM2.5 concentration is lower. As PM2.5 concentration increases, the precision for inputs of coherent state squeezed state decreases faster, and then the two precisions tend to be the same while the concentration is higher.     

Switching response of dual-output Mach–Zehnder modulator in channel-interleaved photonic analog-to-digital converter

This Letter theoretically and experimentally studies the response of photonic switching in a channel-interleaved photonic analog-to-digital converter(PADC) with high sampling rate and wide input frequency range. A figure of merit(FoM) is introduced to evaluate the switching response of the PADC when a dual-output Mach–Zehnder modulator(MZM) serves as the photonic switch to parallelize the sampled pulse train into two channels. After the optimization of the FoM and utilization of the channel-mismatch compensation algorithm,the system bandwidth of PADC is expanded and the signal-to-distortion ratio is enhanced.     

Photon wave function formalism for analysis of Mach–Zehnder interferometer and sum-frequency generation

Biakynicki-Birula introduced a photon wave function similar to the matter wave function that satisfies the Schrödinger equation. Its second quantization form can be applied to investigate nonlinear optics at nearly full quantum level. In this paper, we applied the photon wave function formalism to analyze both linear optical processes in the well-known Mach–Zehnder interferometer and nonlinear optical processes for sum-frequency generation in dispersive and lossless medium. Results by photon wave function formalism agree with the well-established Maxwell treatments and existing experimental verifications.     

Mach–Zehnder interferometer with squeezed and EPR entangled optical fields

We study a scheme for Mach-Zehnder(MZ) interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer.Two-mode squeezed states can be changed into two types of inputs for MZ interferometer:two squeezed states and Einstein-Podolsky-Rosen(EPR) entangled states.The interference patterns of the MZ interferometer vary periodically as the relative phase of the two arms of the interferometer is scanned,and are measured by the balanced homodyne detection system.Our experiments show that there are different interference patterns and periodicity of the output quantum states for two cases which depend on the relative phase of input optical fields.Since MZ interferometer can be used to realize some quantum operations,this work will have the important applications in quantum information and metrology.     

Full quantum mechanical analysis of atomic three-grating Mach–Zehnder interferometry

Atomic three-grating Mach–Zehnder interferometry constitutes an important tool to probe fundamental aspects of the quantum theory. There is, however, a remarkable gap in the literature between the oversimplified models and robust numerical simulations considered to describe the corresponding experiments. Consequently, the former usually lead to paradoxical scenarios, such as the wave–particle dual behavior of atoms, while the latter make difficult the data analysis in simple terms. Here these issues are tackled by means of a simple grating working model consisting of evenly-spaced Gaussian slits. As is shown, this model suffices to explore and explain such experiments both analytically and numerically, giving a good account of the full atomic journey inside the interferometer, and hence contributing to make less mystic the physics involved. More specifically, it provides a clear and unambiguous picture of the wavefront splitting that takes place inside the interferometer, illustrating how the momentum along each emerging diffraction order is well defined even though the wave function itself still displays a rather complex shape. To this end, the local transverse momentum is also introduced in this context as a reliable analytical tool. The splitting, apart from being a key issue to understand atomic Mach–Zehnder interferometry, also demonstrates at a fundamental level how wave and particle aspects are always present in the experiment, without incurring in any contradiction or interpretive paradox. On the other hand, at a practical level, the generality and versatility of the model and methodology presented, makes them suitable to attack analogous problems in a simple manner after a convenient tuning.     

Error scrutiny of measuring coefficients of refractive indices and Soret coefficients using Mach–Zehnder interferometer

No matter how vigilantly an experiment is performed, errors always there inside the experimental results. Since the results of laser based optical experiments are somewhat loftier in precision, commonly, sources of errors are mistreated. However, ample error scrutiny is vital in quantifying of physical parameters of liquids such as Soret and diffusion coefficients. There are two types of experimental errors, explicitly, systematic error and random error. Systematic error is associated to the apparatus and cannot be enhanced by recurrent experiments. Frequent systematic errors in Mach–Zehnder Interferometer (MZI) techniques originate from stability of laser wavelength, resolution of the electronics component etcetera. Random error is interrelated to the variation in the equivalent measurements of repeating experiment. Resolution of electronic components likewise constructs random errors by providing diverse values in the recurring experiment. Foremost, random error of MZI is caused by the environmental circumstances such as nonconformity of background light, air temperature, and air humidity. In this current amendment, a meticulous error analysis has been accomplished for evaluating thermodiffusion or Soret coefficients of hydrocarbon binary mixtures. Based on our knowledge, such a completed error scrutiny for measuring Soret coefficients using MZI does not yet exist in the literature. Study reveals that the utmost error of measuring Soret coefficient using MZI is less than 0.22%.     

All-optical negabinary adders using Mach–Zehnder interferometer

In contrast to optoelectronics, all-optical adders are proposed where all-optical signals are used to represent the input numbers and the control signals. In addition, the all-optical adders use the negabinary modified signed-digit number representation (an extension of the negabinary number system) to represent the input digits. Further, the ultra-speed of the designed circuits is achieved due to the use of ultra-fast all-optical switching property of the semiconductor optical amplifier and Mach–Zehnder interferometer (SOA–MZI). Furthermore, two-bit per digit binary encoding scheme is employed to represent the trinary values of the negabinary modified signed-digits.     

Intensity modulation in two Mach–Zehnder interferometers using plasma dispersion in silicon-on-insulator

We present comparative measurements of two Mach–Zehnder interferometers, one with Y-junction couplers and the other with MMI couplers, both developed in silicon-on-insulator technology and using plasma dispersion effect for light phase modulation. Measurements of fiber-to-fiber losses, absorption coefficient, output intensity vs. time and extinction ratio vs. frequency have been performed at λ=1.3 μm and at λ=1.55 μm. Results are reported and discussed in this paper. Received: 18 May 2001 / Revised version: 24 September2001 / Published online: 30 October 2001     

Switching of one beam by another in a Kerr type nonlinear Mach–Zehnder interferometer

This paper investigates switching of one beam by another in a Kerr type nonlinear Mach–Zehnder interferometer (NMZI) with two input ports and one output port. The present investigation has been carried out using the beam propagation method (BPM). The paper presents a detailed account on the procedures used to choose the parameters of the NMZI to make it behave like a NOT gate (inverter), an AND gate, an amplifier and a wavelength converter. The paper also gives details on the manipulation of the operating inputs of the NMZI to desired values. It is shown that the operating values of both the inputs of the NMZI can simultaneously be increased/decreased by decreasing/increasing the nonlinearity coefficient of nonlinear arm of the NMZI. Variation of NMZI length varies the operating value of only the first input, keeping the second unchanged, while variation of NMZI offset varies the operating value of only the second, keeping the first unchanged. The paper also gives a detailed account on amplification of the NMZI amplifier/wavelength converter. The present investigation is useful from the scientific as well as engineering point of view.