Universal control of four singlet-triplet qubits

Abstract

The coherent control of interacting spins in semiconductor quantum dots is of strong interest for quantum information processing as well as for studying quantum magnetism from the bottom up. Here, we present a $2\times 4$ germanium quantum dot array with full and controllable interactions between nearest-neighbor spins. As a demonstration of the level of control, we define four singlet-triplet qubits in this system and show two-axis single-qubit control of each qubit and SWAP-style two-qubit gates between all neighbouring qubit pairs, yielding average single-qubit gate fidelities of 99.49(8)-99.84(1)% and Bell state fidelities of 73(1)-90(1)%. Combining these operations, we experimentally implement a circuit designed to generate and distribute entanglement across the array. A remote Bell state with a fidelity of 75(2)% and concurrence of 22(4)% is achieved. These results highlight the potential of singlet-triplet qubits as a competing platform for quantum computing and indicate that scaling up the control of quantum dot spins in extended bilinear arrays can be feasible.

In the updated version, data on single- and two-qubit gate fidelities, as well as two-qubit Bell state fidelities, have been added

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Cited by in corpus (23)

• Operating semiconductor quantum processors with hopping spins
• Single-step high-fidelity three-qubit gates by anisotropic chiral interactions
• Fully autonomous tuning of a spin qubit
• Dephasing of planar Ge hole spin qubits due to 1/$\text{f}$ charge noise
• Quantum geometric protocols for fast high-fidelity adiabatic state transfer
• A spinless spin qubit
• Mitigation of exchange cross-talk in dense quantum dot arrays
• Operating two exchange-only qubits in parallel
• A 2x2 quantum dot array in silicon with fully tuneable pairwise interdot coupling
• Electrical readout of spins in the absence of spin blockade
• Multi-qubit DC gates over an inhomogeneous array of quantum dots
• Single-shot latched readout of a quantum dot qubit using barrier gate pulsing
• Polarimetry With Spins in the Solid State
• Hole spin splitting in a Ge quantum dot with finite barriers
• Variability of hole spin qubits in planar Germanium
• Highly Tunable Two-Qubit Interactions in Si/SiGe Quantum Dots by Interchanging the Roles of Qubit-Defining Gates
• Quantum gates in coupled quantum dots controlled by coupling modulation
• Limitations of the $g$-tensor formalism of semiconductor spin qubits
• Dressed basis sets for the modeling of exchange interactions in double quantum dots
• Two qubit gate with macroscopic singlet-triplet qubits in synthetic spin-one chains in InAsP quantum dot nanowires
• Triplet-assisted leakage during singlet-triplet qubit readout with a quantum point contact
• Negative exchange interaction in Si quantum dot arrays via valley-phase induced ${\mathbb{Z}}_2$ gauge field
• Four-state discrimination for a pair of spin qubits via gate reflectometry