Program with Abstracts > Monday

Welcome and Introduction    —  Mo  13:30-14:00

On the role of coherence for quantum computational advantage

Hugo Thomas et al. (Quandela, LIP6, ENS, inria, Edinburgh)    —  Mo  15:00-15:30

Quantifying the resources available to a quantum computer appears to be necessary to separate quantum from classical computation. Among them, entanglement, magic and coherence are arguably of great significance. We introduce path coherence as a measure of the coherent paths interferences arising in a quantum computation. Leveraging the sum-over-paths formalism, we obtain a classical algorithm for estimating quantum transition amplitudes, the complexity of which scales with path coherence. As path coherence relates to the hardness of classical simulation, it provides a new perspective on the role of coherence in quantum computational advantage. Beyond their fundamental significance, our results have practical applications for simulating large classes of quantum computations with classical computers.

Pauli Propagation: a computational framework for simulating noisy and noiseless quantum circuits 

Armando Angrisani (EPFL) & Victor Martinez (ENS Lyon, IBM France)    —  Mo  16:00-16:45

Understanding the capabilities of classical simulation methods is essential for identifying scenarios where quantum computers offer a genuine advantage. This not only ensures that quantum resources are deployed efficiently — only when truly necessary — but also opens the door to offloading certain subroutines onto classical hardware.

Motivated by these considerations, our recent works develop classical algorithms for simulating and surrogating quantum circuits. Our approach is grounded in Pauli Propagation, a computational framework that leverages Pauli-path methods within the Heisenberg picture. While previous works on Pauli-path simulation have primarily targeted circuits subject to depolarizing noise, we significantly broaden the scope by extending classical simulability to both noiseless circuits and those affected by arbitrary local noise, including non-unital channels.

Taken together, our results demonstrate that Pauli Propagation is a powerful and scalable framework for the classical simulation and surrogation of quantum circuits. In contrast to other techniques — such as stabilizer simulation or tensor network approaches — Pauli Propagation can maintain tractable computational costs even in the presence of high-dimensional or chaotic quantum dynamics.

Universal algorithm for transforming Hamiltonian eigenvalues

Mio Murao (Tokyo University)    —  Mo  16:45-17:15

In this work, we provide a new way of manipulating Hamiltonians, by transforming their eigenvalues while keeping their eigenstates unchanged. We develop a universal algorithm that deterministically implements any desired (suitably differentiable) function on the eigenvalues of any unknown Hamiltonian, whose positive-time and negative-time dynamics are given as a black box. Our algorithm uses correlated randomness to efficiently combine two subroutines---namely controlization and Fourier series simulation---exemplifying a general compilation procedure that we develop. The time complexity of our algorithm is significantly reduced via said compilation technique compared to a naïve concatenation of the subroutines and outperforms similar methods based on the quantum singular value transformation.

Roundtable  featuring session speakers    —  Mo  17:15-17:45