A bstract We propose that finite cutoff regions of holographic spacetimes represent quantum circuits map between boundary states at different times and Wilsonian cutoffs, the complexity those is given by gravitational action. The optimal circuit minimizes This a generalization both “complexity equals volume” conjecture to unoptimized circuits, path integral optimization cutoffs. Using tools fro...

Variational quantum algorithms that are used for machine learning rely on the ability to automatically differentiate parametrized circuits with respect underlying parameters. Here we propose rules differentiating (unitaries) arbitrary generators. Unlike standard parameter-shift rule valid unitaries generated by operators spectra limited at most two unique eigenvalues (represented involutory and...

Topological quantum computation is a promising technique to achieve large-scale, error-corrected computation. Quantum hardware is used to create a large, 3-dimensional lattice of entangled qubits while performing computation requires strategic measurement in accordance with a topological circuit specification. The specification is a geometric structure that defines encoded information and fault...

An efficient coding circuit is given for the perfect quantum-error correction of a single quantum bit ~qubit! against arbitrary one-qubit errors within a five-qubit code. The circuit presented employs a double ‘‘classical’’ code, i.e., one for bit flips and one for phase shifts. An implementation of this coding circuit on an ion-trap quantum computer is described that requires 26 laser pulses. ...

We propose a quantum-circuit refrigerator (QCR) based on photon-assisted quasiparticle tunneling through single normal-metal–insulator–superconductor (NIS) junction. In contrast to previous studies with multiple junctions and an additional charge island for the QCR, we directly connect NIS junction inductively shunted electrode of superconducting microwave resonator making device immune low-fre...

We show how to construct a fast quantum circuit for computing the sum of two n-bit binary numbers with few qubits. The constructed circuit uses O(n/ logn) ancillary qubits and its depth and size are O(logn) and O(n), respectively. The number of ancillary qubits is asymptotically less than that in Draper et al.’s quantum carry-lookahead adder, and the depth and size are asymptotically the same a...

One promising approach for scalable quantum computing is to use an alloptical architecture, in which the qubits are represented by photons and manipulated by mirrors and beam splitters. So far, researchers have demonstrated this method, called Linear Optical Quantum Computing, on a very small scale by performing operations using just a few photons. In an attempt to scale up this method to large...