# A 10-qubit solid-state spin register with quantum memory up to one minute

## TL;DR

This paper demonstrates a 10-qubit solid-state spin register with long coherence times up to 63 seconds, enabling advanced quantum information processing and networks with high-fidelity control and entanglement.

## Contribution

The authors develop decoherence-protected gates and realize a large, fully connected 10-qubit register with long coherence times, surpassing previous multi-qubit control capabilities.

## Key findings

- Achieved a 10-qubit quantum register in diamond with full connectivity.
- Demonstrated genuine multipartite entanglement among up to 7 qubits.
- Stored two-qubit entangled states for over 10 seconds.

## Abstract

Spins associated to single defects in solids provide promising qubits for quantum information processing and quantum networks. Recent experiments have demonstrated long coherence times, high-fidelity operations and long-range entanglement. However, control has so far been limited to a few qubits, with entangled states of three spins demonstrated. Realizing larger multi-qubit registers is challenging due to the need for quantum gates that avoid crosstalk and protect the coherence of the complete register. In this paper, we present novel decoherence-protected gates that combine dynamical decoupling of an electron spin with selective phase-controlled driving of nuclear spins. We use these gates to realize a 10-qubit quantum register consisting of the electron spin of a nitrogen-vacancy center and 9 nuclear spins in diamond. We show that the register is fully connected by generating entanglement between all 45 possible qubit pairs, and realize genuine multipartite entangled states with up to 7 qubits. Finally, we investigate the register as a multi-qubit memory. We show coherence times up to 63(2) seconds - the longest reported for a single solid-state qubit - and demonstrate that two-qubit entangled states can be stored for over 10 seconds. Our results enable the control of large quantum registers with long coherence times and therefore open the door to advanced quantum algorithms and quantum networks with solid-state spin qubits.