title: Single-shot readout and relaxation of singlet and triplet states in exchange-coupled 31P electron spins in silicon.
abstract: We present the experimental observation of a large exchange coupling J ≈ 300 μeV between two (31)P electron spin qubits in silicon. The singlet and triplet states of the coupled spins are monitored in real time by a single-electron transistor, which detects ionization from tunnel-rate-dependent processes in the coupled spin system, yielding single-shot readout fidelities above 95%. The triplet to singlet relaxation time T(1) ≈ 4 ms at zero magnetic field agrees with the theoretical prediction for J-coupled 31P dimers in silicon. The time evolution of the two-electron state populations gives further insight into the valley-orbit eigenstates of the donor dimer, valley selection rules and relaxation rates, and the role of hyperfine interactions. These results pave the way to the realization of two-qubit quantum logic gates with spins in silicon and highlight the necessity to adopt gating schemes compatible with weak J-coupling strengths.
authors: Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia.
authors: Juan P
authors: JP
authors: Dehollain
authors: Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia.
authors: Juha T
authors: JT
authors: Muhonen
authors: Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia.
authors: Kuan Y
authors: KY
authors: Tan
authors: Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, Brazil and University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors: Andre
authors: A
authors: Saraiva
authors: Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia.
authors: David N
authors: DN
authors: Jamieson
authors: Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia.
authors: Andrew S
authors: AS
authors: Dzurak
authors: Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia.
authors: Andrea
authors: A
authors: Morello
mesh_terms: D008854:Microscopy, Electron; D010758:Phosphorus / Q000737:chemistry*; D011789:Quantum Theory; D012825:Silicon / Q000737:chemistry*
chemical_list: D010758:Phosphorus; D012825:Silicon