How to Train Your Dragon: Tamed Warping Network for Semantic Video Segmentation

Real-time semantic segmentation on high-resolution videos is challenging due to the strict requirements of speed. Recent approaches have utilized the inter-frame continuity to reduce redundant computation by warping the feature maps across adjacent frames, greatly speeding up the inference phase. However, their accuracy drops significantly owing to the imprecise motion estimation and error accumulation. In this paper, we propose to introduce a simple and effective correction stage right after the warping stage to form a framework named Tamed Warping Network (TWNet), aiming to improve the accuracy and robustness of warping-based models. The experimental results on the Cityscapes dataset show that with the correction, the accuracy (mIoU) significantly increases from 67.3% to 71.6%, and the speed edges down from 65.5 FPS to 61.8 FPS. For non-rigid categories such as "human" and "object", the improvements of IoU are even higher than 18 percentage points

Adiabatic preparation of squeezed states of oscillators and large spin systems coupled to a two-level system

We study a single two-level system coupled resonantly to an oscillator mode or a large spin. By adiabatically turning on a linear driving term on the oscillator or the spin, the eigenstates of the system change character and its ground state evolves into squeezed states of the oscillator or the spin. The robust generation of such states is of interest in many experimental systems with applications for sensing and quantum information processing

Blueprint for quantum computing using electrons on helium

We present a blueprint for building a fault-tolerant quantum computer using the spin states of electrons on the surface of liquid helium. We propose to use ferromagnetic micropillars to trap single electrons on top of them and to generate a local magnetic field gradient. Introducing a local magnetic field gradient hybridizes charge and spin degrees of freedom, which allows us to benefit from both the long coherence time of the spin state and the long-range Coulomb interaction that affects the charge state. We present concrete schemes to realize single- and two-qubit gates and quantum-non-demolition read-out. In our framework, the hybridization of charge and spin degrees of freedom is large enough to perform fast qubit gates and small enough not to degrade the coherence time of the spin state significantly, which leads to the realization of high-fidelity qubit gates

Efficient Non-Learning Similar Subtrajectory Search

Similar subtrajectory search is a finer-grained operator that can better capture the similarities between one query trajectory and a portion of a data trajectory than the traditional similar trajectory search, which requires the two checked trajectories are similar to each other in whole. Many real applications (e.g., trajectory clustering and trajectory join) utilize similar subtrajectory search as a basic operator. It is considered that the time complexity is O(mn^2) for exact algorithms to solve the similar subtrajectory search problem under most trajectory distance functions in the existing studies, where m is the length of the query trajectory and n is the length of the data trajectory. In this paper, to the best of our knowledge, we are the first to propose an exact algorithm to solve the similar subtrajectory search problem in O(mn) time for most of widely used trajectory distance functions (e.g., WED, DTW, ERP, EDR and Frechet distance). Through extensive experiments on three real datasets, we demonstrate the efficiency and effectiveness of our proposed algorithms.Comment: VLDB 202

Coherent control of charged particle systems strongly interacting with microwave photons

Coherent control of charged particle systems using electromagnetic field is an exciting area of research that can lead to new elements for quantum technologies. However, the choice of a suitable system to realize such applications is limited because of the often unavoidable presence of dissipation and decoherence. One condensed matter system where these problems are minimised is the system of surface electrons on liquid helium. This thesis aims to contribute to achieving coherent control of the quantum states of orbital motion of electrons on helium using quantized electromagnetic field in an optical resonator. In particular, I have studied the strong coupling regime of interaction between the cyclotron motion of electrons and the microwave photons in a Fabry-Perot resonator and provided a detailed analysis of experiments carried out in the Quantum Dynamics Unit at OIST using both classical and quantum formalisms. The agreement between both formalisms demonstrated the mean-value nature of the observed normal mode splitting phenomenon. As a theoretical proposal, I have studied the generation of squeezed states and spin-squeezed states of a harmonic oscillator and of an ensembles of two-level-systems, respectively, which is strongly coupled to a twolevel system. In this work I will discuss a special case of the Jaynes-Cummings model driven by an external field and its analogue in which a two-level system is coupled to a collective large spin. This can be seen as a relevant proposal for electrons on helium with coupling between their cyclotron motion and the surface-bound states. Finally, I have studied the surface electrons on helium with a coupling introduced by an inplane magnetic field. I have shown that this leads to a renormalization of the energy spectrum of coupled orbital motion and have made a number of predictions which were confirmed in a subsequent experiment. This work therefore opens doors to explore the physics in the strong coupling regime between the electrons’ surface-bound states and photons in microwave resonators.Okinawa Institute of Science and Technology Graduate Universit

Analytical formulation of the second-order derivative of energy for orbital-optimized variational quantum eigensolver: application to polarizability

We develop a quantum-classical hybrid algorithm to calculate the analytical second-order derivative of the energy for the orbital-optimized variational quantum eigensolver (OO-VQE), which is a method to calculate eigenenergies of a given molecular Hamiltonian by utilizing near-term quantum computers and classical computers. We show that all quantities required in the algorithm to calculate the derivative can be evaluated on quantum computers as standard quantum expectation values without using any ancillary qubits. We validate our formula by numerical simulations of quantum circuits for computing the polarizability of the water molecule, which is the second-order derivative of the energy with respect to the electric field. Moreover, the polarizabilities and refractive indices of thiophene and furan molecules are calculated as a testbed for possible industrial applications. We finally analyze the error-scaling of the estimated polarizabilities obtained by the proposed analytical derivative versus the numerical one obtained by the finite difference. Numerical calculations suggest that our analytical derivative may require fewer measurements (runs) on quantum computers than the numerical derivative to achieve the same fixed accuracy.Comment: 34 + 4 page