RT Journal Article
SR Electronic
T1 Demonstration of Entanglement of Electrostatically Coupled Singlet-Triplet Qubits
JF Science
JO Science
FD American Association for the Advancement of Science
SP 202
OP 205
DO 10.1126/science.1217692
VO 336
IS 6078
A1 Shulman, M. D.
A1 Dial, O. E.
A1 Harvey, S. P.
A1 Bluhm, H.
A1 Umansky, V.
A1 Yacoby, A.
YR 2012
UL http://science.sciencemag.org/content/336/6078/202.abstract
AB The basic building block of a quantum computer, a qubit, has been realized in many physical settings, each of which has its advantages and drawbacks. Solid-state spin qubits interact weakly with their environment and each other, leading not only to long coherence times but also to difficulties in performing multiqubit operations. Shulman et al. (p. 202) used a double quantum dot to produce a singlet-triplet qubit, where the two quantum states available are a singlet and a triplet formed by two spin-1/2 electrons. Two such qubits are then entangled by electrical gating, which affects the charge configuration of one qubit and that, in turn, influences the electric field experienced by the other. This type of two-qubit entanglement is essential for further development of quantum computing in these systems.Quantum computers have the potential to solve certain problems faster than classical computers. To exploit their power, it is necessary to perform interqubit operations and generate entangled states. Spin qubits are a promising candidate for implementing a quantum processor because of their potential for scalability and miniaturization. However, their weak interactions with the environment, which lead to their long coherence times, make interqubit operations challenging. We performed a controlled two-qubit operation between singlet-triplet qubits using a dynamically decoupled sequence that maintains the two-qubit coupling while decoupling each qubit from its fluctuating environment. Using state tomography, we measured the full density matrix of the system and determined the concurrence and the fidelity of the generated state, providing proof of entanglement.