Quantum Tomography at Colliders: With or Without Decays

TL;DR

This paper proposes a novel method for quantum state tomography at particle colliders using production kinematics instead of decays, potentially improving statistical accuracy in quantum measurements.

Contribution

It introduces a kinematic approach to quantum tomography at colliders, offering an alternative to decay-based methods and analyzing its advantages and limitations.

Findings

Kinematic approach provides sufficient information for quantum tomography.

Compared to decay methods, the kinematic approach can be more statistically optimal.

The study highlights the trade-offs between kinematic and decay-based quantum state reconstruction.

Abstract

The interpretation of groups of particle spins at colliders as quantum states has opened up the possibility of using colliders for quantum information. While most efforts have focused on utilizing the decays of the particles to infer their spins to reconstruct the quantum density matrix, we show that the production kinematics of the particles provides sufficient information about the spins to establish quantum tomography without using the decays. We perform a comparative study, highlighting the advantages and disadvantages of using this "kinematic approach" relative to the usual "decay approach." Since the kinematic approach leverages the simplicity of scattering kinematics, this approach promises to achieve the optimal statistical results for quantum tomography at colliders.