Quantum Technology Initiative Journal Club

Thursday 5 Nov 2026, 16:00 → 17:00 Europe/Zurich

513/R-070 - Openlab Space (CERN)

Cenk Tüysüz (CERN), Michele Grossi (CERN)

Weekly Journal Club meetings organised in the framework of the CERN Quantum Technology Initiative (QTI) to present and discuss scientific papers in the field of quantum science and technology. The goal is to help researchers keep track of current findings and walk away with ideas for their own research. Some previous knowledge of quantum physics would be helpful, but is not required to follow the talks.

To propose a paper for discussion, contact: michele.grossi@cern.ch

16:00 → 17:00 CERN QTI Journal CLUB

Conveners: Cenk Tüysüz (CERN), Dr Michele Grossi (CERN)

16:00 Graph Architectures for Anticoncentration and Correlator Visibility in Two-Local IQP Born Machines

Abstract:
Training quantum generative models classically and deploying them on quantum hardware for sampling can reduce training costs and enable larger models while retaining the possibility of a sampling advantage. We use graph-theoretic methods to study two-local IQP circuits, represented by simple undirected graphs whose vertices correspond to qubits with single-qubit $R_Z$ gates and whose edges correspond to two-qubit $R_{ZZ}$ phase gates. We ask which graph structures combine collision anticoncentration with initialization variance that decays at most subexponentially in the number of qubits for every fixed-weight Pauli-$Z$ correlator. Collision anticoncentration describes output distributions whose probability mass is spread broadly across bitstrings and is an ingredient in standard arguments for quantum sampling advantage. We study its ensemble-averaged form under independent, uniformly distributed, unshared singleton and edge angles. Building on established expressions for the ensemble collision factor and correlator variance, we explore graph families that support this coexistence. We also consider stronger inverse-polynomial variance guarantees. To assess the cost of deploying circuits from these graph families on quantum hardware, we compare compilation costs across different hardware coupling maps.

Speaker: Väinö Mehtola (VTT)