Elements of Quantum Computing

Tzvetan S. Metodi, Frederic T. Chong

Paolo Rocca, Nicola Anselmi, Giacomo Oliveri +2 more

Thinning antenna arrays through quantum Fourier transform (QFT) is proposed. Given the lattice of the candidate locations for the array elements, the problem of selecting which antenna location has to be either occupied or not by an array element is formulated in the quantum computing (QC) framework and then addressed with an ad-hoc design method based on a suitable implementation of the QFT algorithm. Representative numerical results are presented and discussed to point out the features and the advantages of the proposed QC-based thinning technique.

Paola Zizzi

A causal set C can describe a discrete spacetime, but this discrete spacetime is not quantum, because C is endowed with Boolean logic, as it does not allow cycles. In a quasi-ordered set Q, cycles are allowed. In this paper, we consider a subset QC of a quasi-ordered set Q, whose elements are all the cycles. In QC, which is endowed with quantum logic, each cycle of maximal outdegree N in a node, is associated with N entangled qubits. Then QC describes a quantum computing spacetime. This structure, which is non-local and non-casual, can be understood as a proto-spacetime. Micro-causality and locality can be restored in the subset U of Q whose elements are unentangled qubits which we interpret as the states of quantum spacetime. The mapping of quantum spacetime into proto-spacetime is given by the action of the XOR gate. Moreover, a mapping is possible from the Boolean causal set into U by the action of the Hadamard gate. In particular, the causal order defined on the elements of U induces the causal evolution of spin networks.

Shilpa Narasimhan, Dominic Messina, Henrique Oyama +1 more

A major challenge to determining the applicability (and potential outperformance over classical computers) of a quantum computer (QC) within chemical manufacturing processes is quantum noise. Computations by a QC are error-prone due to the influence of quantum noise inherent to the hardware. Errors in control inputs may destabilize a chemical process and lead to unsafe conditions for manufacturing personnel and the environment. The response of a process with control implemented on a QC to errors due to noise must be investigated thoroughly. In this work, the impacts of control input errors due to quantum noise on a process are modeled as bounded additive exogenous signals. Process and control element dynamics dictate the response of the process due to perturbations from exogenous signals. A theoretical analysis of the influence of process and control element dynamics on the response of a process to errors in control implemented on a QC is presented. Using simulations of a process example, a demonstration of the interplay between process response to noise, process dynamics, and control valve dynamics is illustrated. The results evaluate, for a specific process, aspects of how process and control element dynamics may mitigate the impact of noise.

Daowen Qiu