Suppose that a quantum circuit with K elementary gates is known for a unitary matrix U , and assume that U is a scalar matrix for some positive integer m. We show that a function of U can be realized on a quantum computer with at most O(mK + m log m) elementary gates. The functions of U are realized by a generic quantum circuit, which has a particularly simple structure. Among other results, we...

Mapping a circuit of reversible gates to a circuit of elementary quantum gates is a key step in synthesizing quantum realizations of Boolean functions. The library containing NOT, controlled-NOT and controlled square-root-of-NOT gates has been considered extensively. In this paper, we extend the library to include fourth-root-of-NOT gates. Experimental results using REVLIB benchmark circuits sh...

This report aims at presenting the research program and to review the literature describing quantum computing, quantum fault tolerance issues and classical fault injection. Thus, previous work is presented together with future research directions. The proposed PhD research program aims at developing a methodology for simulation based fault injection for quantum circuits. Through simulation, I o...

We review the recent progress in direct active cooling of quantum-electric degrees freedom engineered circuits, or quantum-circuit refrigeration. In 2017, invention a refrigerator (QCR) based on photon-assisted tunneling quasiparticles through normal-metal--insulator--superconductor junction inspired series experimental studies demonstrating following main properties: (i) direct-current (dc) bi...

Notions of circuit complexity and cost play a key role in quantum computing simulation where they capture the (weighted) minimal number gates that is required to implement unitary. Similar notions also become increasingly prominent high energy physics study holography. While entanglement have general little implications for unitary, this note, we discuss simple such relationship when both state...

Abstract We consider quantum chaos diagnostics of the variational circuit states at random parameters and explore their connection to expressibility optimizability. By measuring operator spreading coefficient eigenvalue spectrum modular Hamiltonian reduced density matrix, we identify emergence universal matrix ensembles in high-depth states. The that use spectrum, e.g. entanglement entropy, tur...