Physical qubits from charged particles: IR divergences in quantum information

TL;DR

This paper investigates how soft photon effects in QED influence the construction of physical charged qubits, addressing infrared divergences and proposing a dressed formalism to define gauge-invariant, divergence-free qubits for quantum information.

Contribution

It introduces a dressed formalism for constructing physical charged qubits that are gauge invariant and free from infrared divergences, improving the understanding of charged qubits in QED.

Findings

Dressed charged qubits have correct asymptotic behavior.

The formalism yields gauge-invariant, divergence-free qubits.

Soft photon corrections impact entanglement measures.

Abstract

We consider soft photons effects (IR structure of QED) on the construction of physical qubits. Soft-photons appear when we build charged qubits from the asymptotic states of QED. This construction is necessary in order to include the effect of soft photons on entanglement measures. The nonexistence of free charged particles (due to the long range of QED interactions) lead us to question the sense of the very concept of free charged qubit. In this letter, using the "dressing" formalism, we build physical charged qubits from dressed fields which have the correct asymptotic behavior, are gauge invariant, their propagators have a particle pole structure and are free from infrared divergences. Finally, we discuss the impact of the soft corrections on the entanglement measures.