Introduction to Quantum Gates : Implementation of Single and Multiple Qubit Gates

A quantum gate or quantum logic gate is an elementary quantum circuit working on a small number of qubits. It means that quantum gates can grasp two primary feature of quantum mechanics that are entirely out of reach for classical gates : superposition and entanglement. In simpler words quantum gates are reversible. In classical computing sets of logic gates are connected to construct digital circuits. Similarly, quantum logic gates operates on input states that are generally in superposition states to compute the output. In this paper the authors will discuss in detail what is single and multiple qubit gates and scope and challenges in quantum gates.

Research and Application of Encryption System Based on Quantum Circuit for Mobile Internet Security

Nowadays, the IoT technology is developing rapidly. In order to protect the information security of the IoT, this paper applies the characteristics of quantum circuit, such as high complexity and no feedback, into the field of encryption technology, and designed a encryption system based on quantum circuit. The system uses quantum circuit to construct the encryption algorithm, and realizes the mathematical operations and transformation in quantum logic which can be realized through quantum logic gates. Encryption system of quantum circuit can improve the encryption complexity, and its anti-attack ability is ( -1)! times of the traditional method, thus it can effectively protect the information security of the IoT. In order to increase the practicability of the system, this paper designed an interface module to facilitate the interaction of the system with the outside world .What’s more, the IoT application system is designed in which the validity and correctness of the encryption system are verified.

Research and application of encryption system based on quantum circuit for mobile internet security#

Nowadays, the IoT technology is developing rapidly. In order to protect the information security of the IoT, this paper applies the characteristics of quantum circuit, such as high complexity and no feedback, into the field of encryption technology, and designed a encryption system based on quantum circuit. The system uses quantum circuit to construct the encryption algorithm, and realizes the mathematical operations and transformation in quantum logic which can be realized through quantum logic gates. Encryption system of quantum circuit can improve the encryption complexity, and its anti-attack ability is ( -1)! times of the traditional method, thus it can effectively protect the information security of the IoT. In order to increase the practicability of the system, this paper designed an interface module to facilitate the interaction of the system with the outside world .What’s more, the IoT application system is designed in which the validity and correctness of the encryption system are verified.

Designs for a two-dimensional Si quantum dot array with spin qubit addressability

Electron spins in Si are an attractive platform for quantum computation, backed with their scalability and fast, high-fidelity quantum logic gates. Despite the importance of two-dimensional integration with efficient connectivity between qubits for medium- to large-scale quantum computation, however, a practical device design that guarantees qubit addressability is yet to be seen. Here, we propose a practical 3 × 3 quantum dot device design and a larger-scale design as a longer-term target. The design goal is to realize qubit connectivity to the four nearest neighbors while ensuring addressability. We show that a 3 × 3 quantum dot array can execute four-qubit Grover’s algorithm more efficiently than the one-dimensional counterpart. To scale up the two-dimensional array beyond 3 × 3, we propose a novel structure with ferromagnetic gate electrodes. Our results showcase the possibility of medium-sized quantum processors in Si with fast quantum logic gates and long coherence times.

High-performance cavity-enhanced quantum memory with warm atomic cell

High-performance quantum memory for quantized states of light is a prerequisite building block of quantum information technology. Despite great progresses of optical quantum memories based on interactions of light and atoms, physical features of these memories still can not satisfy the requirement for applications in practical quantum information systems, since all of them suffer from trade off between memory efficiency and excess noise. Here, we report a high-performance cavity-enhanced electromagnetically-induced-transparency memory with warm atomic cell in which a scheme of optimizing the spatial and temporal modes based on the time-reversal approach is applied. A quantum memory with the efficiency up to 78 + 1% and the noise level close to quantum noise limit has been experimentally achieved. The realized quantum memory platform has been capable of preserving quantized optical states, and thus is ready to be applied in quantum information systems, such as distributed quantum logic gates and quantum-enhanced atomic magnetometry.

Experimental realization of phase-controlled dynamics with hybrid digital–analog approach

Quantum simulation can be implemented in pure digital or analog ways, each with their pros and cons. By taking advantage of the universality of a digital route and the efficiency of analog simulation, hybrid digital–analog approaches can enrich the possibilities for quantum simulation. We use a hybrid approach to experimentally perform a quantum simulation of phase-controlled dynamics resulting from a closed-contour interaction (CCI) within certain multi-level systems in superconducting quantum circuits. Due to symmetry constraints, such systems cannot host an inherent CCI. Nevertheless, by assembling analog modules corresponding to their natural evolutions and specially designed digital modules constructed from standard quantum logic gates, we can bypass such constraints and realize an effective CCI in these systems. Based on this realization, we demonstrate a variety of related and interesting phenomena, including phase-controlled chiral dynamics, separation of chiral enantiomers, and a mechanism to generate entangled states based on CCI.