1,538 Hits in 2.4 sec

Quantum coherent feedback control with photons [article]

Haijin Ding, Guofeng Zhang
2022 arXiv   pre-print
The purpose of this paper is to study two-photon dynamics induced by the coherent feedback control of a cavity quantum electrodynamics (cavity QED) system coupled to a waveguide with a terminal mirror. In this set-up, the two-level system in the cavity can work as a photon source, and the photon emitted into the waveguide can re-interact with the cavity-QED system many times after perfectly reflected by the terminal mirror of the waveguide, during which the feedback can tune the number of the
more » ... otons in the waveguide and cavity. We analyze the dynamics of two-photon processes in this coherent feedback network in two scenarios: the continuous mode coupling scheme and the discrete periodic mode coupling scheme between the waveguide and cavity. The difference of these coupling schemes is due to the transmission of fields between the waveguide and cavity, and the their relative scales. Specifically, in the continuous mode coupling scheme, the generation of two-photon states is influenced by the length of the feedback loop of the waveguide and the coupling strength between the waveguide and the cavity QED system. By tuning the length of the waveguide and the coupling strength, we are able to generate two-photon states efficiently. In the discrete periodic mode coupling scheme, the Rabi oscillation in the cavity can be stabilized and there are no notable two-photon states in the waveguide.
arXiv:2206.01445v1 fatcat:xkpcvkyguncvjiurzet47ne4jm

An Improved Quantum Projection Filter [article]

Qing Gao and Guofeng Zhang and Ian R. Petersen
2019 arXiv   pre-print
., Zhang G., Petersen I. R. (2019). An exponential quantum projection filter for open quantum systems. Automatica, 99, 59-68.], by adding an optimality analysis result.  ... 
arXiv:1909.13524v1 fatcat:ihfn664jlvco7jnhr7xvh3vpwu

Quantum Criticality in the Biased Dicke Model [article]

Hanjie Zhu, Guofeng Zhang, Heng Fan
2015 arXiv   pre-print
The biased Dicke model describes a system of biased two-level atoms coupled to a bosonic field, and is expected to produce new phenomena that are not present in the original Dicke model. In this paper, we study the critical properties of the biased Dicke model in the classical oscillator limits. For the finite-biased case in this limit, We present analytical results demonstrating that the excitation energy does not vanish for arbitrary coupling. This indicates that the second order phase
more » ... ion is avoided in the biased Dicke model, which contrasts to the original Dicke model. We also analyze the squeezing and the entanglement in the ground state, and find that a finite bias will strongly modify their behaviors in the vicinity of the critical coupling point.
arXiv:1512.06531v1 fatcat:u3izwp3n6naevgwizx5xst6bne

TRIM proteins in neuroblastoma

Yonghu Xu, Zihan Zhang, Guofeng Xu
2019 Bioscience Reports  
Neuroblastoma (NB) is the most common extracranial solid tumor in childhood. Outcome for children with high-risk NB remains unsatisfactory. Accumulating evidence suggests that tripartite motif (TRIM) family proteins express diversely in various human cancers and act as regulators of oncoproteins or tumor suppressor proteins. This review summarizes the TRIM proteins involving in NB and the underlying molecular mechanisms. We expect these new insights will provide important implications for the treatment of NB by targeting TRIM proteins.
doi:10.1042/bsr20192050 pmid:31820796 pmcid:PMC6928532 fatcat:njfkw6kfgjhvhniz36ftyd4drm

Single-photon quantum filtering with multiple measurements [article]

Zhiyuan Dong, Guofeng Zhang, Nina H. Amini
2018 arXiv   pre-print
The single-photon quantum filtering problems have been investigated recently with applications in quantum computing. In practice, the detector responds with a quantum efficiency of less than unity since there exists some mode mismatch between the detector and the system, and the single-photon signal may be corrupted by quantum white noise. Consequently, quantum filters based on multiple measurements are designed in this paper to improve the estimation performance. More specifically, the
more » ... g equations for a two-level quantum system driven by a single-photon input state and under multiple measurements are presented in this paper. Four scenarios, 1) two diffusive measurements with Q-P quadrature form, 2) two diffusive measurements with Q-Q quadrature form, 3) diffusive plus Poissonian measurements, and 4) two Poissonian measurements, are considered. It is natural to compare the filtering results, i.e., measuring single channel or both channels, which one is better? By the simulation where we use a single photon to excite an atom, it seems that multiple measurements enable us to excite the atom with higher probability than only measuring single channel. In addition, measurement back-action phenomenon is revealed by the simulation results.
arXiv:1801.03267v1 fatcat:xxtuuw77s5gqfdeaviy6meosfi

Linear quantum systems: a tutorial [article]

Guofeng Zhang, Zhiyuan Dong
2022 arXiv   pre-print
The purpose of this tutorial is to give a brief introduction to linear quantum control systems. The mathematical model of linear quantum control systems is presented first, then some fundamental control-theoretic notions such as stability, controllability and observability are given, which are closely related to several important concepts in quantum information science such as decoherence-free subsystems, quantum non-demolition variables, and back-action evasion measurements. After that,
more » ... Gaussian states are introduced, in particular, an information-theoretic uncertainty relation is presented which often gives a better bound for mixed Gaussian states than the well-known Heisenberg uncertainty relation. The quantum Kalman filter is presented for quantum linear systems, which is the quantum analogy of the Kalman filter for classical (namely, non-quantum-mechanical) linear systems. The quantum Kalman canonical decomposition for quantum linear systems is recorded, and its application is illustrated by means of a recent experiment. As single- and multi-photon states are useful resources in quantum information technology, the response of quantum linear systems to these types of input is presented. Finally, coherent feedback control of quantum linear systems is briefly introduced, and a recent experiment is used to demonstrate the effectiveness of quantum linear systems and networks theory.dback control of quantum linear systems is briefly introduced, and a recent experiment is used to demonstrate the effectiveness of quantum linear systems and networks theory.
arXiv:2205.04080v2 fatcat:76tlnuqhvjaspmtczbzdovx5ye

On the Control of Flying Qubits [article]

Wen-Long Li ang Guofeng Zhang, Re-Bing Wu
2021 arXiv   pre-print
The control of flying quantum bits (qubits) carried by traveling quantum fields is crucial for coherent information transmission in quantum networks. In this paper, we develop a general framework for modeling the generation, catching and transformation processes of flying qubits. We introduce the quantum stochastic differential equation (QSDE) to describe the flying-qubit input-output relations actuated by a standing quantum system. Under the continuous time-ordered photon-number basis, the
more » ... nite-dimensional QSDE is reduced to a low-dimensional deterministic non-unitary differential equation for the state evolution of the standing system, and the outgoing flying-qubit states can be calculated via randomly occurring quantum jumps. This makes it possible, as demonstrated by examples of flying-qubit generation and transformation, to analyze general cases when the number of excitations is not reserved. The proposed framework lays the foundation for the design of flying-qubit control systems from a control theoretic point of view, within which advanced control techniques can be incorporated for practical applications.
arXiv:2111.00143v1 fatcat:qzxt3njmnvh7veh5bxxxop6ury

Energy cost for controlling complex networks [article]

Gaopeng Duan, Aming Li, Tao Meng, Guofeng Zhang, Long Wang
2018 arXiv   pre-print
The controllability of complex networks has received much attention recently, which tells whether we can steer a system from an initial state to any final state within finite time with admissible external inputs. In order to accomplish the control in practice at the minimum cost, we must study how much control energy is needed to reach the desired final state. At a given control distance between the initial and final states, existing results present the scaling behavior of lower bounds of the
more » ... nimum energy in terms of the control time analytically. However, to reach an arbitrary final state at a given control distance, the minimum energy is actually dominated by the upper bound, whose analytic expression still remains elusive. Here we theoretically show the scaling behavior of the upper bound of the minimum energy in terms of the time required to achieve control. Apart from validating the analytical results with numerical simulations, our findings are feasible to the scenario with any number of nodes that receive inputs directly and any types of networks. Moreover, more precise analytical results for the lower bound of the minimum energy are derived in the proposed framework. Our results pave the way to implement realistic control over various complex networks with the minimum control cost.
arXiv:1809.06067v1 fatcat:5gjyd27zjzctlaq5nuo3zivzeq

Analysis of Quantum Linear Systems' Response to Multi-photon States [article]

Guofeng Zhang
2013 arXiv   pre-print
The results presented here generalize those in the single-photon setting studied in (Milburn, 2008) and (Zhang and James, 2013}).  ...  Zhang) .  ...  & James, 2011 , Zhang & James, 2012 .  ... 
arXiv:1311.0357v1 fatcat:6hamsmzidzdungz5ulkyqkf2mq

OnePose: One-Shot Object Pose Estimation without CAD Models [article]

Jiaming Sun, Zihao Wang, Siyu Zhang, Xingyi He, Hongcheng Zhao, Guofeng Zhang, Xiaowei Zhou
2022 arXiv   pre-print
We propose a new method named OnePose for object pose estimation. Unlike existing instance-level or category-level methods, OnePose does not rely on CAD models and can handle objects in arbitrary categories without instance- or category-specific network training. OnePose draws the idea from visual localization and only requires a simple RGB video scan of the object to build a sparse SfM model of the object. Then, this model is registered to new query images with a generic feature matching
more » ... k. To mitigate the slow runtime of existing visual localization methods, we propose a new graph attention network that directly matches 2D interest points in the query image with the 3D points in the SfM model, resulting in efficient and robust pose estimation. Combined with a feature-based pose tracker, OnePose is able to stably detect and track 6D poses of everyday household objects in real-time. We also collected a large-scale dataset that consists of 450 sequences of 150 objects.
arXiv:2205.12257v1 fatcat:pvnfopvttjforjswrumniw56ua

Geometric measure of entanglement of multipartite mixed states [article]

Shenglong Hu, Liqun Qi, Yisheng Song, Guofeng Zhang
2012 arXiv   pre-print
The geometric measure of entanglement of a pure state, defined by its distance to the set of pure separable states, is extended to multipartite mixed states. We characterize the nearest disentangled mixed state to a given mixed state with respect to this measure by a system of equations. The entanglement eigenvalue for a mixed state is introduced. For a given mixed state, we show that its nearest disentangled mixed state is associated with its entanglement eigenvalue.
arXiv:1204.4317v1 fatcat:xaabz5qhpbbilj6bwv4yue2kqe

PVO: Panoptic Visual Odometry [article]

Weicai Ye, Xinyue Lan, Shuo Chen, Yuhang Ming, Xingyuan Yu, Hujun Bao, Zhaopeng Cui, Guofeng Zhang
2022 arXiv   pre-print
We present a novel panoptic visual odometry framework, termed PVO, to achieve a more comprehensive modeling of the scene's motion, geometry, and panoptic segmentation information. PVO models visual odometry (VO) and video panoptic segmentation (VPS) in a unified view, enabling the two tasks to facilitate each other. Specifically, we introduce a panoptic update module into the VO module, which operates on the image panoptic segmentation. This Panoptic-Enhanced VO module can trim the interference
more » ... of dynamic objects in the camera pose estimation by adjusting the weights of optimized camera poses. On the other hand, the VO-Enhanced VPS module improves the segmentation accuracy by fusing the panoptic segmentation result of the current frame on the fly to the adjacent frames, using geometric information such as camera pose, depth, and optical flow obtained from the VO module. These two modules contribute to each other through a recurrent iterative optimization. Extensive experiments demonstrate that PVO outperforms state-of-the-art methods in both visual odometry and video panoptic segmentation tasks. Code and data are available on the project webpage: tt .
arXiv:2207.01610v1 fatcat:pqps6zj4tjgttfckeanb3pjvae

Classical and Quantum Stochastic Models of Resistive and Memristive Circuits [article]

John E. Gough, Guofeng Zhang
2015 arXiv   pre-print
The purpose of this paper is to examine stochastic Markovian models for circuits in phase space for which the drift term is equivalent to the standard circuit equations. In particular we include dissipative components corresponding to both a resistor and a memristor in series. We obtain a dilation of the problem for which is canonical in the sense that the underlying Poisson Brackets structure is preserved under the stochastic flow. We do this first of all for standard Wiener noise, but also
more » ... at the problem using a new concept of symplectic noise where the Poisson structure is extended to the noise as well as the circuit variables, and in particular where we have canonically conjugate noises. Finally we construct a dilation which describes the quantum mechanical analogue.
arXiv:1510.08243v1 fatcat:i5tsecbljfgx5bfx4m4dpjgwz4

The Kalman Decomposition for Linear Quantum Stochastic Systems [article]

Symeon Grivopoulos, Guofeng Zhang, Ian R. Petersen, John Gough
2016 arXiv   pre-print
Zhang is with the Department of Applied Mathematics, The Hong Kong Polytechnic University, Hong Kong John Gough is with the Department of Physics, Aberystwyth University, Wales  ...  Putting everything together, we have that are with the School of Engineering and Information Technology, UNSW Canberra, Canberra BC 2610, Australia, Guofeng  ... 
arXiv:1609.05982v1 fatcat:4f7vfooyk5b6pp7m64rbguyyn4

On realization theory of quantum linear systems

John E. Gough, Guofeng Zhang
2015 Automatica  
More discussions on physical realizability of quantum linear systems can be found in, e.g., [James, Nurdin & Petersen, 2008] ; [Zhang & James, 2011] ; [Zhang & James, 2012 ].  ...  ; [Matyas, et al., 2011] ; [Tian, 2012] ; [Zhang, et al., 2013] ; linear system, namely, the number of system oscillators.  ... 
doi:10.1016/j.automatica.2015.06.023 fatcat:sf5ho2g6xff5le6rq47pjcldnm
« Previous Showing results 1 — 15 out of 1,538 results