Warit Asavanant

Quantum computation promises applications that are thought to be impossible with classical computation. To realize practical quantum computation, the following three properties will be necessary: universality, scalability, and fault-tolerance. Universality is the ability to execute arbitrary multi-input quantum algorithms. Scalability means that computational resources such as logical qubits can be increased without requiring exponential increase in physical resources. Lastly, fault-tolerance is

Continuous-variable optical quantum computation has seen much progress in recent years. In particular, cluster states---the universal resource for measurement-based quantum computation---have been realized in a scalable fashion using the time-domain multiplexing method. To utilize the cluster states in actual quantum computation, the measurement bases need to be programmed according to the desired computation. In addition, as the information is encoded in time in the time-domain multiplexing met

We propose and analyze a setup to tailor the wave functions of quantum states. Our setup is based on the quantum teleportation circuit, but instead of the usual two-mode squeezed state, a two-mode non-Gaussian entangled state is used. Using this setup, we can generate various classes of quantum states such as Schr\"odinger cat states, four-component cat states, superpositions of Fock states, and cubic phase states. These results demonstrate the versatility of our system as a state generator and

Quantum entanglement is a fundamental resource for various quantum applications and generation of large-scale entanglement is a key quantum technology. In recent years, continuous-variable optical systems have shown promising results in this direction, thanks to deterministic generation and multiplexing via rich degrees of freedom naturally occurring in the optical system. In this paper, we review the generation and applications of multipartite optical quantum entanglement. We begin with a theor

This book is a current and rare treatment of the theoretical and experimental aspects of one of the most promising approaches to quantum computation—continuous-variable (CV) quantum computation using optical systems. In addition to its pedagogical value to those new to quantum computing, it is also a practical handbook for both experimentalists and theorists working in the field. Optical Quantum Computers: A Route to Practical Continuous Variable Quantum Information Processing summarizes many re

Optical switches and rerouting networks are considered essential in optical quantum computers where they are used for injection and dejection of the necessary quantum states into an optical quantum computer. Practical optical switches and rerouting networks are, however, experimentally challenging as they must have extremely low loss, small switching time, high repetition rate, and minimum optical nonlinearity, requirements that are difficult to achieve simultaneously. In this paper, we present

Among various approaches toward quantum computation, measurement-based quantum computation (MBQC) multiplexed in time domain is currently a promising method for addressing the need for scalability. MBQC requires two components: cluster states and programmable measurements. With time-domain multiplexing, the former has been realized on an ultra-large-scale. The latter, however, has remained unrealized, leaving the large-scale cluster states unused. In this work, we make such a measurement system