QIC Abstracts

 Vol.20 No.5&6, May 1, 2020

Research Articles:

Two-outcome synchronous correlation sets and Connes' embedding problem (pp361-374)
          
Travis B. Russell
We show that Connes' embedding problem is equivalent to the weak Tsirelson problem in the setting of two-outcome synchronous correlation sets. We further show that the extreme points of two-outcome synchronous correlation sets can be realized using a certain class of universal C*-algebras. We examine these algebras in the three-experiment case and verify that the strong and weak Tsirelson problems have affirmative answers in that setting.

Persistent homology analysis of multiqubit entanglement (pp375-399)
          
Ricardo Mengoni, Alessandra Di Pierro, Leleh Memarzadeh, and Stefano Mancini
We introduce a homology-based technique for the { classification of multiqubit state vectors with genuine entanglement}. In our approach, we associate  state vectors to data sets by introducing a metric-like measure in terms of bipartite entanglement, and investigate the persistence of homologies at different scales. This leads to a novel  classification of multiqubit entanglement. The relative occurrence frequency of various classes of entangled states is also shown.

Algebraic units, anti-unitary symmetries, and a small catalogue of SICs (pp400-417)
          
Ingemar Bengtsson
In complex vector spaces maximal sets of equiangular lines, known as SICs, are related to real quadratic number fields in a dimension dependent way. If the dimension is of the form $n^2+3$ the base field has a fundamental unit of negative norm, and there exists a SIC with anti-unitary symmetry. We give eight examples of exact solutions of this kind, for which we have endeavoured to make them as simple as we can---as a belated reply to the referee of an earlier publication, who claimed that our exact solution in dimension 28 was too complicated to be fit to print. An interesting feature of the simplified solutions is that the components of the fiducial vectors largely consist of algebraic units.

Realization of Quantum Oracles using Symmetries of Boolean Functions (pp418-448)
          
Peng Gao, Yiwei Li, Marek Perkowski, and Xiaoyu Song
Designing a quantum oracle is an important step in practical realization of Grover algorithm, therefore it is useful to create methodologies to design oracles. Lattice diagrams are regular two-dimensional structures that can be directly mapped onto a quantum circuit. We present a quantum oracle design methodology based on lattices. The oracles are designed with a proposed method using generalized Boolean symmetric functions realized with lattice diagrams. We also present a decomposition-based algorithm that transforms non-symmetric functions into symmetric or partially symmetric functions. Our method, which combines logic minimization, logic decomposition, and mapping, has lower quantum cost with fewer ancilla qubits. Overall, we obtain encouraging synthesis results superior to previously published data.

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