scholarly journals High-fidelity quantum gates for OAM single qudits on quantum memory

2022 ◽  
Vol 19 (2) ◽  
pp. 025202
Author(s):  
E A Vashukevich ◽  
E N Bashmakova ◽  
T Yu Golubeva ◽  
Yu M Golubev
Keyword(s):  
Quantum Systems ◽  
Quantum Memory ◽  
Quantum Gates ◽  
High Fidelity ◽  
Optimal Conditions ◽  
Memory Scheme ◽  
Different Dimensions ◽  
Single Qudit ◽  
High Level ◽  
Promising Avenue

Abstract The application of high-dimensional quantum systems (qudits) in quantum computing and communications seems to be a promising avenue due to the possibility of increasing the amount of information encoded in one physical carrier. In this work, we propose a method for implementing single-qudit gates for qudits based on light modes with orbital angular momentum (OAM). Method for logical qudits encoding, which ensures the quasi-cyclicity of operations, is introduced. Based on the protocol for converting the OAM of light in the Raman quantum memory scheme (Vashukevich et al 2020 Phys. Rev. A 101 033830), we show that the considered gates provide an extremely high level of fidelity of single-qudit transformations. We also compare quantum gates’ properties for systems of different dimensions and find the optimal conditions for carrying out transformations in the protocol under consideration.

scholarly journals High-fidelity composite quantum gates for Raman qubits

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Boyan T. Torosov ◽  
Nikolay V. Vitanov
Keyword(s):  
Quantum Gates ◽  
High Fidelity

Transfer Reinforcement Learning for Autonomous Driving

2021 ◽  
Vol 31 (3) ◽  
pp. 1-26
Author(s):  
Aravind Balakrishnan ◽  
Jaeyoung Lee ◽  
Ashish Gaurav ◽  
Krzysztof Czarnecki ◽  
Sean Sedwards
Keyword(s):  
Decision Making ◽  
Reinforcement Learning ◽  
Transfer Problem ◽  
Autonomous Driving ◽  
High Fidelity ◽  
Rule Based ◽  
High Level ◽  
Real Vehicle

Reinforcement learning (RL) is an attractive way to implement high-level decision-making policies for autonomous driving, but learning directly from a real vehicle or a high-fidelity simulator is variously infeasible. We therefore consider the problem of transfer reinforcement learning and study how a policy learned in a simple environment using WiseMove can be transferred to our high-fidelity simulator, W ise M ove . WiseMove is a framework to study safety and other aspects of RL for autonomous driving. W ise M ove accurately reproduces the dynamics and software stack of our real vehicle. We find that the accurately modelled perception errors in W ise M ove contribute the most to the transfer problem. These errors, when even naively modelled in WiseMove , provide an RL policy that performs better in W ise M ove than a hand-crafted rule-based policy. Applying domain randomization to the environment in WiseMove yields an even better policy. The final RL policy reduces the failures due to perception errors from 10% to 2.75%. We also observe that the RL policy has significantly less reliance on velocity compared to the rule-based policy, having learned that its measurement is unreliable.

scholarly journals Topological protection of biphoton states

Science ◽  
2018 ◽  
Vol 362 (6414) ◽  
pp. 568-571 ◽  
Author(s):  
Andrea Blanco-Redondo ◽  
Bryn Bell ◽  
Dikla Oren ◽  
Benjamin J. Eggleton ◽  
Mordechai Segev
Keyword(s):  
Quantum Information ◽  
Thermal Environment ◽  
Propagation Constant ◽  
Quantum Systems ◽  
Quantum Gates ◽  
Scattering Loss ◽  
Spatial Features ◽  
Quantum Optical ◽  
Nontrivial Topology ◽  
Large Quantum

The robust generation and propagation of multiphoton quantum states are crucial for applications in quantum information, computing, and communications. Although photons are intrinsically well isolated from the thermal environment, scaling to large quantum optical devices is still limited by scattering loss and other errors arising from random fabrication imperfections. The recent discoveries regarding topological phases have introduced avenues to construct quantum systems that are protected against scattering and imperfections. We experimentally demonstrate topological protection of biphoton states, the building block for quantum information systems. We provide clear evidence of the robustness of the spatial features and the propagation constant of biphoton states generated within a nanophotonics lattice with nontrivial topology and propose a concrete path to build robust entangled states for quantum gates.

High Fidelity Modeling of the Acceleration of a Turboshaft Engine During a Restart

2018 ◽  
Author(s):  
Antoine Ferrand ◽  
Marc Bellenoue ◽  
Yves Bertin ◽  
Radu Cirligeanu ◽  
Patrick Marconi ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Combustion Efficiency ◽  
High Fidelity ◽  
Gas Generator ◽  
Idle Speed ◽  
Flight Mode ◽  
System States ◽  
Secondary Air ◽  
Turboshaft Engine ◽  
High Level

In order to decrease the fuel consumption, a new flight mode is being considered for twin-engine helicopters, in which one engine is put into sleeping mode (a mode in which the gas generator is kept at a stabilized, sub-idle speed by means of an electric motor, with no combustion), while the remaining engine operates at nominal load. The restart of the engine in sleeping mode is therefore deemed critical for safety reasons. This efficient new flight mode has raised the interest in the modeling of the restart of a turboshaft engine. In this context, the initial conditions of the simulations are better known relative to a ground start, in particular the air flow through the gas generator is constant, the fuel and oil system states are known and temperatures of the casings are equal to ambient. During the restart phase of the engine, the gas generator speed is kept at constant speed until the light-up is detected by a rise in inter-turbine temperature, then the starter torque increases, accelerating the engine towards idle speed. In this paper, the modeling of the acceleration of the gas generator from light-up to idle and above idle speeds is presented. Details on the light-up process are not addressed here. The study is based on the high-fidelity aero-thermodynamic restart model that is currently being developed for a 2000 horse power, free turbine turboshaft. In this case, the term high-fidelity refers not only to the modeling of the flow path components but it also includes all the subsystems, secondary air flows and controls with a high level of detail. The physical phenomena governing the acceleration of the turboshaft engine following a restart — mainly the transient evolution of the combustion efficiency and the power loss by heat soakage — are discussed in this paper and modeling solutions are presented. The results of the simulations are compared to engine test data, highlighting that the studied phenomena have an impact on the acceleration of the turboshaft engine and that the model is able to correctly predict acceleration trends.

scholarly journals High-fidelity optical quantum gates based on type-II double quantum dots in a nanowire

2019 ◽  
Vol 99 (16) ◽  
Author(s):  
Masoomeh Taherkhani ◽  
Morten Willatzen ◽  
Emil V. Denning ◽  
Igor E. Protsenko ◽  
Niels Gregersen
Keyword(s):  
Quantum Dots ◽  
Quantum Gates ◽  
Double Quantum ◽  
High Fidelity ◽  
Type Ii ◽  
Double Quantum Dots

scholarly journals Optical Quantum Memory and its Applications in Quantum Communication Systems

2020 ◽  
Vol 125 ◽  
Author(s):  
Lijun Ma ◽  
Oliver Slattery ◽  
Xiao Tang
Keyword(s):  
Communication Systems ◽  
Quantum Systems ◽  
Quantum Memory ◽  
Research Progress ◽  
Quantum Communications ◽  
Quantum Repeater ◽  
Quantum Networks ◽  
And Performance ◽  
The Impact ◽  
Photon Source

Optical quantum memory is a device that can store the quantum state of photons and retrieve it on demand and with high fidelity. It is emerging as an essential device to enhance security, speed, scalability, and performance of many quantum systems used in communications, computing, metrology, and more. In this paper, we will specifically consider the impact of optical quantum memory on quantum communications systems. Following a general overview of the theoretical and experimental research progress in optical quantum memory, we will outline its role in quantum communications, including as a photon source, photon interference, quantum key distribution (QKD), quantum teleportation, quantum repeater, and quantum networks.

scholarly journals Regeneration Performance of Activated Carbon for Desulfurization

2020 ◽  
Vol 10 (17) ◽  
pp. 6107
Author(s):  
Zhiguo Sun ◽  
Menglu Wang ◽  
Jiaming Fan ◽  
Yue Zhou ◽  
Li Zhang
Keyword(s):  
Activated Carbon ◽  
Material Surface ◽  
Test Results ◽  
Optimal Conditions ◽  
Adsorption Efficiency ◽  
Thermal Regeneration ◽  
So2 Removal ◽  
Sulfur Capacity ◽  
Desulfurization Efficiency ◽  
High Level

This study explored the regenerated performance of activated carbon (AC) as SO2 adsorbent. The optimal conditions of SO2 removal were determined by experiment, and then the adsorption efficiency of AC was studied by a method of thermal regeneration. The characteristics of regenerated AC were analyzed by Brunauer-Emmett-Teller (BET) and Scanning Electron Microscopy (SEM) methods. The test results showed that the most suitable adsorption conditions were using 4 g of activated carbon, 1.65 L/min gas flue rate, and 5% O2. During the ten regenerations, the desulfurization efficiency and sulfur capacity of AC still maintained a high level. The characterization results showed that the increase of material surface area and pore volume were 101 m2 g−1, and 0.13 cm3 g−1, respectively, after the cycles.

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