Single-qubit quantum memory exceeding ten-minute coherence time

• Published in: Nature photonics Vol. 11; no. 10; pp. 646 - 650
• Main Authors: Wang, Ye, Um, Mark, Zhang, Junhua, An, Shuoming, Lyu, Ming, Zhang, Jing-Ning, Duan, L.-M., Yum, Dahyun, Kim, Kihwan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-10-2017; Nature Publishing Group
• Subjects: 639/624/400/482; 639/766/36; 639/766/483/2802; 639/766/483/481; Applied and Technical Physics; Coherence; Computers; Decoupling; Letter; Noise; Physics; Physics and Astronomy; Quantum computers; Quantum computing; Quantum phenomena; Quantum Physics; Quantum theory; Qubits (quantum computing); Variation
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-017-0007-1

A long-time quantum memory capable of storing and measuring quantum information at the single-qubit level is an essential ingredient for practical quantum computation and communication
1
,
2
. Currently, the coherence time of a single qubit is limited to less than 1 min, as demonstrated in trapped ion systems
3
–
5
, although much longer coherence times have been reported in ensembles of trapped ions
6
,
7
and nuclear spins of ionized donors
8
,
9
. Here, we report the observation of a coherence time of over 10 min for a single qubit in a
171
Yb
+
ion sympathetically cooled by a
138
Ba
+
ion in the same Paul trap, which eliminates the problem of qubit-detection inefficiency from heating of the qubit ion
10
,
11
. We also apply a few thousand dynamical decoupling pulses to suppress ambient noise from magnetic-field fluctuations and phase noise from the local oscillator
8
,
9
,
12
–
16
. The long-time quantum memory of the single trapped ion qubit would be the essential component of scalable quantum computers
1
,
17
,
18
, quantum networks
2
,
19
,
20
and quantum money
21
,
22
.
The longest coherence time of a single qubit of more than ten minutes is observed in a
171
Yb
+
ion. After sympathetically cooling the
171
Yb
+
ion qubit with a
138
Ba
+
ion, noise from magnetic-field fluctuations and the local oscillator is suppressed by a dynamic decoupling scheme.