Interferometric Power Research Articles

Robustness of interferometric power to sudden death

In this paper, we study the dissipative dynamics of interferometric power as a discord-like measure in Markovian environments such as dephasing, depolarizing, and generalized amplitude damping. Moreover, we compare the dynamics of interferometric power and entanglement by choosing the proper initial conditions. Our study shows that interferometric power decays asymptotically in all cases where the sudden death of entanglement appears. Therefore, quantum metrology based on interferometric power is more robust than entanglement.

Enhanced Gaussian interferometric power, entanglement and Gaussian quantum steering in magnonics system with squeezed light

In this study, we propose a scheme to improve quantum correlations (QCs) between two magnons in a tripartite magnonical system. We use Gaussian interferometric power (GIP) to quantify QCs beyond entanglement. Additionally, Gaussian quantum steering is discussed. We investigate the enhancement of QCs via a squeezing parameter and an optical parametric amplifier (OPA). The Mancini criterion is considered to confirm the presence of shared entanglement between the two magnons. We observed a squeezing of about 7 dB for the first magnon. Additionally, the squeezed vacuum field and the OPA improve the generation of genuine tripartite entanglement. We hope that current experimental technology will allow the proposed scheme to be implemented.

Compact Low Loss Ribbed Asymmetric Multimode Interference Power Splitter

Optical power splitters (OPSs) are utilized extensively in integrated photonic circuits, drawing significant interest in research on power splitters with adjustable splitting ratios. This paper introduces a compact, low-loss 1 × 2 asymmetric multimode interferometric (MMI) optical power splitter on a silicon-on-insulator (SOI) platform. The device is simulated using the finite difference method (FDM) and eigenmode expansion solver (EME). It is possible to attain various output power splitting ratios by making the geometry of the MMI central section asymmetric relative to the propagation axis. Six distinct optical power splitters are designed with unconventional splitting ratios in this paper, which substantiates that the device can achieve any power splitter ratios (PSRs) in the range of 95:5 to 50:50. The dimensions of the multimode section were established at 2.9 × (9.5–10.9) μm. Simulation results show a range of unique advantages of the device, including a low extra loss of less than 0.4 dB, good fabrication tolerance, and power splitting ratio fluctuation below 3% across the 1500 nm to 1600 nm wavelength span.

Quantum thermometry based on interferometric power

In the field of quantum thermometry, usually temperature is estimated by the framework of quantum metrology. In this work, an alternative approach to quantum thermometry is suggested, based on interferometric power (IP). IP is defined as the worst-case quantum Fisher information in a double-channel interferometer. Specifically, the time evolution of the IP for a two-qubit state as a probe contacting with a finite-temperature bath is considered. The IP dynamics of the probe with three kinds of initial states (i.e., entangled, separable, and mixed) strongly depend on the bath temperature. The dynamical evolution of IP would be measured experimentally, considering that the IP is a measurable quantity in the experiment. Thus, the IP dynamics can be adopted to extract the value of the bath temperature directly. In this sense, the IP could be exploited as a quantum thermometer.

Quantum correlations and entanglement in coupled optomechanical resonators with photon hopping via Gaussian interferometric power analysis

Quantum correlations that surpass entanglement are of great importance in the realms of quantum information processing and quantum computation. Essentially, for quantum systems prepared in pure states, it is difficult to differentiate between quantum entanglement and quantum correlation. Nonetheless, this indistinguishability is no longer holds for mixed states. To contribute to a better understanding of this differentiation, we have explored a simple model for both generating and measuring these quantum correlations. Our study concerns two macroscopic mechanical resonators placed in separate Fabry–Pérot cavities, coupled through the photon hopping process. this system offers a comprehensively way to investigate and quantify quantum correlations beyond entanglement between these mechanical modes. The key ingredient in analyzing quantum correlation in this system is the global covariance matrix. It forms the basis for computing two essential metrics: the logarithmic negativity ( ENm ) and the Gaussian interferometric power ( PGm ). These metrics provide the tools to measure the degree of quantum entanglement and quantum correlations, respectively. Our study reveals that the Gaussian interferometric power ( PGm ) proves to be a more suitable metric for characterizing quantum correlations among the mechanical modes in an optomechanical quantum system, particularly in scenarios featuring resilient photon hopping.

Quantum interferometric power versus quantum correlations in a graphene layer system with a scattering process under thermal noise

Cutting-edge quantum processing technology is currently exploring the remarkable electronic properties of graphene layers, such as their high mobility and thermal conductivity. Our research is dedicated to investigating the behavior of quantum resources within a graphene layer system with a scattering process, specifically focusing on quantum interferometric power (QIP) and quantum correlations, while taking into account the influence of thermal noise. To quantify these correlations, we employ measures like local quantum uncertainty (LQU) and logarithmic negativity (LN). We examine how factors like temperature, inter-valley scattering processes strength, and other system parameters affect both QIP and quantum correlations. Our results reveal that higher temperatures lead to a reduction in QIP and non-classical correlations within graphene layers. Moreover, it is noteworthy that QIP and LQU respond similarly to changes in temperature, whereas LN is more sensitive to these variations. By optimizing system parameters such as band parameter, wavenumber operators and scattering processes strength, we can mitigate the impact of thermal noise and enhance the quantum advantages of graphene-based quantum processing

Two-qubit quantum nonlocality dynamics induced by interacting of two coupled superconducting flux qubits with a resonator under intrinsic decoherence

This paper explores the dynamics of two spatially separated superconducting flux qubits, initially in a maximally correlated state, without mutual interaction. The system is modeled using the master intrinsic decoherence equation with the flux-qubits-resonator interaction Hamiltonian. The effects of initial state, detuning, and decoherence on the generated oscillatory correlation dynamics and the sudden death-birth phenomenon of the two flux-qubits entanglement are examined. The results demonstrate that qubit-resonator-qubit interactions have a high ability to generate quantum interferometric power and local quantum uncertainty correlations beyond that of concurrence entanglement.

Spectral stacking of radio-interferometric data

Context. Mapping molecular line emission beyond the bright low-J CO transitions is still challenging in extragalactic studies, even with the latest generation of (sub-)millimetre interferometers, such as ALMA and NOEMA. Aims. We summarise and test a spectral stacking method that has been used in the literature to recover low-intensity molecular line emission, such as HCN(1−0), HCO+(1−0), and even fainter lines in external galaxies. The goal is to study the capabilities and limitations of the stacking technique when applied to imaged interferometric observations. Methods. The core idea of spectral stacking is to align spectra of the low S/N spectral lines to a known velocity field calculated from a higher S/N line expected to share the kinematics of the fainter line (e.g. CO(1−0) or 21 cm emission). Then these aligned spectra can be coherently averaged to produce potentially high S/N spectral stacks. Here we used imaged simulated interferometric and total power observations at different S/N levels, based on real CO observations. Results. For the combined interferometric and total power data, we find that the spectral stacking technique is capable of recovering the integrated intensities even at low S/N levels across most of the region where the high S/N prior is detected. However, when stacking interferometer-only data for low S/N emission, the stacks can miss up to 50% of the emission from the fainter line. Conclusions. A key result of this analysis is that the spectral stacking method is able to recover the true mean line intensities in low S/N cubes and to accurately measure the statistical significance of the recovered lines. To facilitate the application of this technique we provide a public Python package, called PYSTACKER.

Quantum interferometric power and non-Markovianity in the decoherence channels

In quantum open systems, non-Markovianity is an important phenomenon that allows a backflow of information from the environment to the system. In this work, we investigate the non-Markovianity problems in two different types of channels, where the system–environment interactions are treated with and without the rotating-wave approximation (RWA). We employ the quantum interferometric power (QIP) to quantify the non-Markovian dynamics, which is the minimal quantum Fisher information obtained by the local unitary evolution in a bipartite system. By the hierarchy equation method, we calculate the dynamical evolution of the QIP in the non-RWA case. The results show that the dynamical behavior under the non-RWA is significantly different from that under the RWA in both weak and strong coupling. Moreover, in the non-RWA case, we also find the nonmonotonic behavior of the non-Markovianity measure with the variation of coupling strength, which is caused by the competition between the rotating-wave terms and the counterrotating-wave terms. As a result, we highlight the importance of the counterrotating-wave terms for the influence of non-Markovianity.

Quantum interferometric power and Bures distance entanglement versus normalized steered coherence under random telegraph noise

This study examines the impact of random telegraph noise on non-separability, non-classicality, and steered coherence in a bipartite system initially prepared in a Gisin state and embedded in both Markovian and non-Markovian environments. To quantify non-separability, we employ the Bures distance entanglement measure ([Formula: see text]); for non-classicality detection, we utilize the quantum interferometric power ([Formula: see text]); and to measure steered coherence, we employ the normalized steered coherence ([Formula: see text]). We analyze the dynamics of these three metrics under the effects of the random telegraph noise through various theoretical and numerical techniques. Our findings demonstrate that the amount of quantum correlations in the system is closely tied to the parameters defining the random telegraph noise and the initial system state. Our results also reveal that all three measures exhibit oscillatory behavior in the non-Markovian regime and monotonic changes with time in the Markovian regime. These results provide a deeper understanding of the robustness and stability of non-separability and coherence under noisy conditions and may have implications for the design of noise-resistant quantum systems.

Local Quantum Uncertainty and Quantum Interferometric Power in an Anisotropic Two-Qubit System

Investigating the favorable configurations for non-classical correlations preservation has remained a hotly debated topic for the last decade. In this regard, we present a two-qubit Heisenberg spin chain system exposed to a time-dependent external magnetic field. The impact of various crucial parameters, such as initial strength and angular frequency of the external magnetic field along with the state’s purity and anisotropy of the spin-spin on the dynamical behavior of quantum correlations are considered. We utilize local quantum uncertainty (LQU) and quantum interferometric power (QIP) to investigate the dynamics of quantum correlations. We show that under the critical angular frequency of the external magnetic field and the spin-spin anisotropy, quantum correlations in the system can be successfully preserved. LQU and QIP suffer a drop as the interaction between the system and field is initiated, however, are quickly regained by the system. This tendency is confirmed by computing a measure of non-classical correlations according to the Clauser–Horne–Shimony–Holt inequality. Notably, the initial and final preserved levels of quantum correlations are only varied when variation is caused in the state’s purity.

Black-box estimation of expanding parameter for de Sitter universe

We study the black-box parameter estimation of expanding parameters and the dynamics of Gaussian interferometric power for the de Sitter space. We find that the state between separated open charts can be employed as a probe state for the black-box quantum metrology. This is nontrivial because the open charts are causally disconnected and classical information can not be exchanged between them according to the general relativity. It is shown that the mass of the scalar field remarkably affects the accuracy of the black-box parameter estimation in the de Sitter space, which is quite different from the flat space case where the mass parameter does not influence the precision of estimation. Quantum discord is found to be a key resource for the estimation of the expanding parameter when there is no entanglement between the initially uncorrelated open charts. It is demonstrated that the role of the probe state between different open charts is quite distinct because the curvature effect of the de sitter space damages quantum resources for the initially correlated probe states, while it generates quantum resources for the initially uncorrelated probe states.

Quantifying quantum correlations in noisy Gaussian channels

The Gaussian states are essential ingredients in many tasks of quantum information processing. The presence of the noises imposes limitations on achieving these quantum protocols. Therefore, examining the evolution of quantum entanglement and quantum correlations under the coherence of Gaussian states in noisy channels is of paramount importance. In this paper, we propose and analyze a scheme that aims to specify and examine the dynamic evolution of the quantum correlations in two-mode Gaussian states submitted to the influence of the Gaussian thermal environment. We describe the time evolution of the quantum correlations in an open system consisting of two coupled bosonic modes embedded in a Gaussian thermal environment. We discuss the influence of the environment in terms of the initial parameters of the input states. The quantum correlations are quantified using Gaussian interferometric power and the Gaussian entanglement of formation. The behavior of these quantum correlations quantifiers is strictly dependent on the parameters of the input states that are employed. We show that the Gaussian interferometric power is a measurement quantifier that can capture the essential quantum correlations beyond quantum entanglement. In addition, we show that the Gaussian interferometric power is less influenced than the Gaussian entanglement of formation.

Dynamically producing asymmetric interferometric power under dephasing

Interferometric power, based on the minimal quantum Fisher information in a black-box interferometer, can be used to measure general quantum correlation in a bipartite system. This paper explores the interferometric power of a two-qubit system in a common bath. It is found that, for an initially separable state, the interferometric power of the system can be produced with the time evolution, even subject to the dephasing environment. Moreover, it is asymmetric with respect to the local evolution implementing on one subsystem or another. Our result would be useful to quantum information processing beyond entanglement, especially in one-sided device-independent task.

Quantum steering and quantum discord under noisy channels and entanglement swapping

Quantum entanglement, quantum discord, and EPR-steering are properties which are considered as valuable resources for fuelling quantum information-theoretic protocols. EPR-steering is a correlation weaker than nonlocality (in the Bell's sense) and yet stronger than entanglement. Quantum discord on the other hand, captures non-classical behaviour beyond that of entanglement, and its study has remained of active research interest during the past two decades. Exploring the behaviour of these quantum correlations in different physical scenarios, like those simulated by open quantum systems, is therefore of crucial importance for understanding their viability for quantum technologies. In this work, we analyse the behaviour of EPR-steering, entanglement, and quantum discord, for partially entangled two-qubit states with coloured noise, introduced by Ameida et al. [1], under various quantum processes. First, we consider the three noisy channel scenarios of; phase damping, generalised amplitude damping and stochastic dephasing channel. Second, we explore their behaviour in an entanglement swapping scenario. We quantify EPR-steering by means of an inequality with three-input two-output measurement settings, and address quantum discord as the interferometric power of quantum states. We discuss the sudden death of steering and entanglement induced by the noisy processes. Additionally, in the case of generalised amplitude damping, a death and revival behaviour can be interpreted in terms of one of the noise's parameters. Second, we contrast the fact that noisy channels in general reduce the amount of correlations present in the system, with the swapping protocol, which displays scenarios where these quantum correlations can be enhanced with respect to the correlations at the initial stage of the protocol. In particular, we present a trade-off between the post-swap amount of correlations and their probability of occurrence.

Local Fisher- and skew-information coherence of two Nitrogen-Vacancy centers induced by two coupled dissipative nanocavities

The paper investigates the dynamics of the quantum interferometric power and Local quantum uncertainty coherences beyond concurrence entanglement between two Nitrogen-Vacancy centers (NVCs) induced by two coupled dissipative nanocavities. A particular engineering design is considered, where each nanocavity contains a coherently driven N-V center and the two nanocavities are initially in a maximally correlated state with different initial two-NVC states. It is found that, for the initial uncorrelated two-NVC state, the generated two-NVC coherence and the entanglement due to the NVC-nanocavity interactions can be enhanced by the increase of the Nitrogen-Vacancy center’s couplings. The cavity dissipations enhance the generation of Fisher and skew information quantumness of the two-NVC state, and accelerate the reduction of the concurrence entanglement. For the initial maximally correlated two-NVC state, the robustness of the two-NVC coherence and the entanglement against the NVC-nanocavity interactions and the dissipation can be enhanced by the two-nanocavity coupling and the two NVC-qubits couplings.

PHANGS–ALMA Data Processing and Pipeline

Abstract We describe the processing of the PHANGS–ALMA survey and present the PHANGS–ALMA pipeline, a public software package that processes calibrated interferometric and total power data into science-ready data products. PHANGS–ALMA is a large, high-resolution survey of CO(2–1) emission from nearby galaxies. The observations combine ALMA’s main 12 m array, the 7 m array, and total power observations, and use mosaics of dozens to hundreds of individual pointings. We describe the processing of the u − v data, imaging and deconvolution, linear mosaicking, combining interferometer and total power data, noise estimation, masking, data product creation, and quality assurance. Our pipeline has a general design and can also be applied to Very Large Array and ALMA observations of other spectral lines and continuum emission. We highlight our recipe for deconvolution of complex spectral line observations, which combines multiscale clean, single-scale clean, and automatic mask generation in a way that appears robust and effective. We also emphasize our two-track approach to masking and data product creation. We construct one set of “broadly masked” data products, which have high completeness but significant contamination by noise, and another set of “strictly masked” data products, which have high confidence but exclude faint, low signal-to-noise emission. Our quality assurance tests, supported by simulations, demonstrate that 12 m+7 m deconvolved data recover a total flux that is significantly closer to the total power flux than the 7 m deconvolved data alone. In the appendices, we measure the stability of the ALMA total power calibration in PHANGS–ALMA and test the performance of popular short-spacing correction algorithms.

A Unified Approach to Local Quantum Uncertainty and Interferometric Power by Metric Adjusted Skew Information

Local quantum uncertainty and interferometric power were introduced by Girolami et al. as geometric quantifiers of quantum correlations. The aim of the present paper is to discuss their properties in a unified manner by means of the metric adjusted skew information defined by Hansen.

Quantum coherence measure based on affinity

Quantification of quantum coherence is a fundamental and key issue in the field of resource theory and quantum information processing. Exploiting an affinity-based metric, in this article, we define a faithful measure of quantum coherence. It is shown that the affinity-based coherence is bounded by that based on fidelity and trace distance. The measure of quantumness in terms of the difference between bipartite coherence and corresponding product state coherence is also identified. Finally, we interpret the operational meaning of the affinity-based coherence as a lower bound of interferometric power of the quantum state.

Measurement-induced nonlocality based on affinity

Measurement-induced nonlocality (MIN), a quantum correlation measure for bipartite systems, is an indicator of maximal global effects due to locally invariant von Neumann projective measurements. It is originally defined as the maximal square of the Hilbert–Schmidt norm of the difference between pre- and post-measurement states. In this article, we propose a new form of MIN based on affinity. This quantity satisfies all the criteria of a bona fide measure of quantum correlation measures. This quantity is evaluated for both arbitrary pure and 2 × n dimensional (qubit–qudit) mixed states. The operational meaning of the proposed quantity is interpreted in terms of the interferometric power of the quantum state. We apply these results on two-qubit mixed states, such as the Werner, isotropic and Bell diagonal states.