Fast multi-qubit gates by adiabatic evolution in interacting excited state manifolds

TL;DR

This paper proposes a method for implementing fast multi-qubit gates using adiabatic evolution along dark eigenstates in interacting excited state manifolds, demonstrating potential for high-fidelity operations in Rydberg atoms and superconducting circuits.

Contribution

It introduces a novel adiabatic approach for multi-qubit gates that surpasses traditional methods in speed and robustness, applicable across various quantum platforms.

Findings

Multi-qubit gates can be implemented with errors below 1%.

The approach is feasible for up to 20 qubits.

Similar gates can be realized in superconducting circuits.

Abstract

Quantum computing and quantum simulation can be implemented by concatenation of one- and two-qubit gates and interactions. For most physical implementations, however, it may be advantageous to explore state components and interactions that depart from this universal paradigm and offer faster or more robust access to more advanced operations on the system. In this article, we show that adiabatic passage along the dark eigenstate of excitation exchange interactions can be used to implement fast multi-qubit Toffoli (C$_k$-NOT) and fan-out (C-NOT$^k$) gates. This mechanism can be realized by simultaneous excitation of atoms to Rydberg levels, featuring resonant exchange interaction. Our theoretical estimates and numerical simulations show that these multi-qubit Rydberg gates are possible with errors below 1% for up to 20 qubits. The excitation exchange mechanism is ubiquitous across experimental platforms and we show that similar multi-qubit gates can be implemented in superconducting circuits.