Paper Quantum computed moments correction to variational estimates Harish J. Vallury, Michael A. Jones, Charles D. Hill, and Lloyd C. L. Hollenberg, Quantum 4, 373 (2020). The variational principle of quantum mechanics is the backbone of hybrid quantum computing for a range of applications. However, as the problem size grows, quantum logic errors and the effec…
Paper Near-optimal ground state preparation Lin Lin and Yu Tong, Quantum 4, 372 (2020). Preparing the ground state of a given Hamiltonian and estimating its ground energy are important but computationally hard tasks. However, given some additional information, these problems ca…
Paper The Prime state and its quantum relatives D. García-Martín, E. Ribas, S. Carrazza, J.I. Latorre, and G. Sierra, Quantum 4, 371 (2020). The Prime state of $n$ qubits, ${|\mathbb{P}_n{\rangle}}$, is defined as the uniform superposition of all the computational-basis states corresponding to prime numbers smaller than $2^n$. This sta…
Paper Un-Weyl-ing the Clifford Hierarchy Tefjol Pllaha, Narayanan Rengaswamy, Olav Tirkkonen, and Robert Calderbank, Quantum 4, 370 (2020). The teleportation model of quantum computation introduced by Gottesman and Chuang (1999) motivated the development of the Clifford hierarchy. Despite its intrinsic value for quantum computin…
Paper Synthesis of CNOT-Dihedral circuits with optimal number of two qubit gates Shelly Garion and Andrew W. Cross, Quantum 4, 369 (2020). In this note we present explicit canonical forms for all the elements in the two-qubit CNOT-Dihedral group, with minimal numbers of controlled-$S$ ($CS$) and controlled-$X$ ($CX$) gates, using the g…
Paper A review of Quantum Cellular Automata Terry Farrelly, Quantum 4, 368 (2020). Discretizing spacetime is often a natural step towards modelling physical systems. For quantum systems, if we also demand a strict bound on the speed of information propagation, we get quant…
Paper Quantum reference frames for general symmetry groups Anne-Catherine de la Hamette and Thomas D. Galley, Quantum 4, 367 (2020). A fully relational quantum theory necessarily requires an account of changes of quantum reference frames, where quantum reference frames are quantum systems relative to which other systems a…
Paper Fast optimization of parametrized quantum optical circuits Filippo M. Miatto and Nicolás Quesada, Quantum 4, 366 (2020). Parametrized quantum optical circuits are a class of quantum circuits in which the carriers of quantum information are photons and the gates are optical transformations. Classically optimizi…
Paper Experimental Comparison of Bohm-like Theories with Different Primary Ontologies Arthur O. T. Pang, Hugo Ferretti, Noah Lupu-Gladstein, Weng-Kian Tham, Aharon Brodutch, Kent Bonsma-Fisher, J. E. Sipe, and Aephraim M. Steinberg, Quantum 4, 365 (2020). The de Broglie-Bohm theory is a hidden-variable interpretation of quantum mechanics which involves particles moving through space along deterministic trajectories. This theory singles out po…
Paper Operational, gauge-free quantum tomography Olivia Di Matteo, John Gamble, Chris Granade, Kenneth Rudinger, and Nathan Wiebe, Quantum 4, 364 (2020). As increasingly impressive quantum information processors are realized in laboratories around the world, robust and reliable characterization of these devices is now more urgent than ever. T…
Paper Information and disturbance in operational probabilistic theories Giacomo Mauro D’Ariano, Paolo Perinotti, and Alessandro Tosini, Quantum 4, 363 (2020). Any measurement is intended to provide $information$ on a system, namely knowledge about its state. However, we learn from quantum theory that it is generally impossible to extract information…
Paper A volumetric framework for quantum computer benchmarks Robin Blume-Kohout and Kevin C. Young, Quantum 4, 362 (2020). We propose a very large family of benchmarks for probing the performance of quantum computers. We call them {volumetric benchmarks} (VBs) because they generalize IBM's benchmark for measurin…
Paper Optimal polynomial based quantum eigenstate filtering with application to solving quantum linear systems Lin Lin and Yu Tong, Quantum 4, 361 (2020). We present a quantum eigenstate filtering algorithm based on quantum signal processing (QSP) and minimax polynomials. The algorithm allows us to efficiently prepare a target eigenstate of a…
Paper On the Alberti-Uhlmann Condition for Unital Channels Sagnik Chakraborty, Dariusz Chruściński, Gniewomir Sarbicki, and Frederik vom Ende, Quantum 4, 360 (2020). We address the problem of existence of completely positive trace preserving (CPTP) maps between two sets of density matrices. We refine the result of Alberti and Uhlmann and derive a necessa…
Paper Composites and Categories of Euclidean Jordan Algebras Howard Barnum, Matthew A. Graydon, and Alexander Wilce, Quantum 4, 359 (2020). We consider possible non-signaling composites of probabilistic models based on euclidean Jordan algebras (EJAs), satisfying some reasonable additional constraints motivated by the desire to…
Paper Always-On Quantum Error Tracking with Continuous Parity Measurements Razieh Mohseninia, Jing Yang, Irfan Siddiqi, Andrew N. Jordan, and Justin Dressel, Quantum 4, 358 (2020). We investigate quantum error correction using continuous parity measurements to correct bit-flip errors with the three-qubit code. Continuous monitoring of errors brings the benefit of a con…
