Quantum

Paper

Self-referenced hologram of a single photon beam

Wiktor Szadowiak, Sanjukta Kundu, Jerzy Szuniewicz, and Radek Lapkiewicz,

Quantum 5, 516 (2021).

Quantitative characterization of the spatial structure of single photons is essential for free-space quantum communication and quantum imaging. We introduce an interferometric technique that…

Paper

Causal influence in operational probabilistic theories

Paolo Perinotti,

Quantum 5, 515 (2021).

We study the relation of causal influence between input systems of a reversible evolution and its output systems, in the context of operational probabilistic theories. We analyse two differe…

Paper

On the distribution of the mean energy in the unitary orbit of quantum states

Raffaele Salvia and Vittorio Giovannetti,

Quantum 5, 514 (2021).

Given a closed quantum system, the states that can be reached with a cyclic process are those with the same spectrum as the initial state. Here we prove that, under a very general assumption…

Paper

Quantum walk-based portfolio optimisation

N. Slate, E. Matwiejew, S. Marsh, and J. B. Wang,

Quantum 5, 513 (2021).

This paper proposes a highly efficient quantum algorithm for portfolio optimisation targeted at near-term noisy intermediate-scale quantum computers. Recent work by Hodson et al. (2019) expl…

Paper

An efficient quantum algorithm for the time evolution of parameterized circuits

Stefano Barison, Filippo Vicentini, and Giuseppe Carleo,

Quantum 5, 512 (2021).

We introduce a novel hybrid algorithm to simulate the real-time evolution of quantum systems using parameterized quantum circuits. The method, named "projected – Variational Quantum Dynamics…

Paper

Causal and compositional structure of unitary transformations

Robin Lorenz and Jonathan Barrett,

Quantum 5, 511 (2021).

The causal structure of a unitary transformation is the set of relations of possible influence between any input subsystem and any output subsystem. We study whether such causal structure ca…

Paper

QED driven QAOA for network-flow optimization

Yuxuan Zhang, Ruizhe Zhang, and Andrew C. Potter,

Quantum 5, 510 (2021).

We present a general framework for modifying quantum approximate optimization algorithms (QAOA) to solve constrained network flow problems. By exploiting an analogy between flow-constraints…

Paper

Resource-Optimized Fermionic Local-Hamiltonian Simulation on a Quantum Computer for Quantum Chemistry

Qingfeng Wang, Ming Li, Christopher Monroe, and Yunseong Nam,

Quantum 5, 509 (2021).

The ability to simulate a fermionic system on a quantum computer is expected to revolutionize chemical engineering, materials design, nuclear physics, to name a few. Thus, optimizing the sim…

Paper

Spacetime Quantum Reference Frames and superpositions of proper times

Flaminia Giacomini,

Quantum 5, 508 (2021).

In general relativity, the description of spacetime relies on idealised rods and clocks, which identify a reference frame. In any concrete scenario, reference frames are associated to physic…

Paper

Momentum Kicks in Imperfect Which-Way Measurement

Neha Pathania and Tabish Qureshi,

Quantum 5, 507 (2021).

There has been an intense debate on the question as to whether a quanton, passing through a double-slit, experiences a 'momentum kick' due to the act of which-way detection. There have been…

Paper

Nonclassical trajectories in head-on collisions

A. Kumar, T. Krisnanda, P. Arumugam, and T. Paterek,

Quantum 5, 506 (2021).

Rutherford scattering is usually described by treating the projectile either classically or as quantum mechanical plane waves. Here we treat them as wave packets and study their head-on coll…

Paper

Energy storage and coherence in closed and open quantum batteries

Francesco Caravelli, Bin Yan, Luis Pedro García-Pintos, and Alioscia Hamma,

Quantum 5, 505 (2021).

We study the role of coherence in closed and open quantum batteries. We obtain upper bounds to the work performed or energy exchanged by both closed and open quantum batteries in terms of co…

Paper

Partially Coherent Direct Sum Channels

Stefano Chessa and Vittorio Giovannetti,

Quantum 5, 504 (2021).

We introduce $\textit{Partially Coherent Direct Sum}$ (PCDS) quantum channels, as a generalization of the already known $\textit{Direct Sum}$ quantum channels. We derive necessary and sufficient…

Paper

Routed quantum circuits

Augustin Vanrietvelde, Hlér Kristjánsson, and Jonathan Barrett,

Quantum 5, 503 (2021).

We argue that the quantum-theoretical structures studied in several recent lines of research cannot be adequately described within the standard framework of quantum circuits. This is in part…

Paper

Quantum Algorithms for Solving Ordinary Differential Equations via Classical Integration Methods

Benjamin Zanger, Christian B. Mendl, Martin Schulz, and Martin Schreiber,

Quantum 5, 502 (2021).

Identifying computational tasks suitable for (future) quantum computers is an active field of research. Here we explore utilizing quantum computers for the purpose of solving differential eq…

Paper

Self-organized topological insulator due to cavity-mediated correlated tunneling

Titas Chanda, Rebecca Kraus, Giovanna Morigi, and Jakub Zakrzewski,

Quantum 5, 501 (2021).

Topological materials have potential applications for quantum technologies. Non-interacting topological materials, such as e.g., topological insulators and superconductors, are classified by…

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