# Decoherence suppression by uncollapsing

## TL;DR

This paper demonstrates that quantum uncollapsing can nearly eliminate qubit decoherence caused by energy relaxation, by using partial measurements to protect and restore the qubit state, with practical implementation in superconducting qubits.

## Contribution

It introduces a method to suppress qubit decoherence through quantum uncollapsing, combining partial measurements and state restoration, applicable to superconducting qubits.

## Key findings

- Decoherence can be nearly suppressed using uncollapsing.
- Trade-off between decoherence suppression and measurement success probability.
- Experimental feasibility with superconducting phase qubits.

## Abstract

We show that the qubit decoherence due to zero-temperature energy relaxation can be almost completely suppressed by using the quantum uncollapsing procedure. To protect a qubit state, a partial quantum measurement moves it towards the ground state, where it is kept during the storage period, while the second partial measurement restores the initial state. This procedure preferentially selects the cases without energy decay events. Stronger decoherence suppression requires smaller selection probability; a desired point in this trade-off can be chosen by varying the measurement strength. The experiment can be realized in a straightforward way using the superconducting phase qubit.