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 $2\times4$ 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.
- Vandersypen, L. etĀ al. Interfacing spin qubits in quantum dots and donorsāhot, dense, and coherent. npj Quantum Inf. 3, 34 (2017).
- Heinrich, A.Ā J. etĀ al. Quantum-coherent nanoscience. Nat. Nanotechnol. 16, 1318ā1329 (2021).
- Gonzalez-Zalba, M. etĀ al. Scaling silicon-based quantum computing using CMOS technology. Nat. Electron. 4, 872ā884 (2021).
- Chatterjee, A. etĀ al. Semiconductor qubits in practice. Nat. Rev. Phys. 3, 157ā177 (2021).
- Review of performance metrics of spin qubits in gated semiconducting nanostructures. Nat. Rev. Phys. 4, 672ā688 (2022).
- Semiconductor spin qubits. Rev. Mod. Phys. 95, 025003 (2023).
- Xue, X. etĀ al. Quantum logic with spin qubits crossing the surface code threshold. Nature 601, 343ā347 (2022).
- Noiri, A. etĀ al. Fast universal quantum gate above the fault-tolerance threshold in silicon. Nature 601, 338ā342 (2022).
- Mills, A.Ā R. etĀ al. Two-qubit silicon quantum processor with operation fidelity exceeding 99%. Sci. Adv. 8, eabn5130 (2022).
- Hendrickx, N.Ā W. etĀ al. A four-qubit germanium quantum processor. Nature 591, 580ā585 (2021).
- Philips, S.Ā G. etĀ al. Universal control of a six-qubit quantum processor in silicon. Nature 609, 919ā924 (2022).
- Lawrie, W. etĀ al. Simultaneous single-qubit driving of semiconductor spin qubits at the fault-tolerant threshold. Nat. Commun. 14, 3617 (2023).
- Shulman, M.Ā D. etĀ al. Demonstration of entanglement of electrostatically coupled singlet-triplet qubits. Science 336, 202ā205 (2012).
- Nichol, J.Ā M. etĀ al. High-fidelity entangling gate for double-quantum-dot spin qubits. npj Quantum Inf. 3, 3 (2017).
- Weinstein, A.Ā J. etĀ al. Universal logic with encoded spin qubits in silicon. Nature 615, 817ā822 (2023).
- Hensgens, T. etĀ al. Quantum simulation of a FermiāHubbard model using a semiconductor quantum dot array. Nature 548, 70ā73 (2017).
- Dehollain, J.Ā P. etĀ al. Nagaoka ferromagnetism observed in a quantum dot plaquette. Nature 579, 528ā533 (2020).
- van Diepen, C.Ā J. etĀ al. Quantum simulation of antiferromagnetic Heisenberg chain with gate-defined quantum dots. Phys. Rev. X. 11, 041025 (2021).
- Wang, C.-A. etĀ al. Probing resonating valence bonds on a programmable germanium quantum simulator. npj Quantum Inf. 9, 58 (2023).
- Jang, W. etĀ al. Individual two-axis control of three singlet-triplet qubits in a micromagnet integrated quantum dot array. Appl. Phys. Lett. 117, 234001 (2020).
- Fedele, F. etĀ al. Simultaneous operations in a two-dimensional array of singlet-triplet qubits. PRX Quantum 2, 040306 (2021).
- Mortemousque, P.-A. etĀ al. Coherent control of individual electron spins in a two-dimensional quantum dot array. Nat. Nanotechnol. 16, 296ā301 (2021).
- Levy, J. Universal quantum computation with spin-1/2121/21 / 2 pairs and Heisenberg exchange. Phys. Rev. Lett. 89, 147902 (2002).
- Petta, J.Ā R. etĀ al. Coherent manipulation of coupled electron spins in semiconductor quantum dots. Science 309, 2180ā2184 (2005).
- Maune, B.Ā M. etĀ al. Coherent singlet-triplet oscillations in a silicon-based double quantum dot. Nature 481, 344ā347 (2012).
- Wu, X. etĀ al. Two-axis control of a singletātriplet qubit with an integrated micromagnet. Proc. Natl. Acad. Sci. U.S.A. 111, 11938ā11942 (2014).
- Jock, R.Ā M. etĀ al. A silicon metal-oxide-semiconductor electron spin-orbit qubit. Nat. Commun. 9, 1768 (2018).
- Cerfontaine, P. etĀ al. Closed-loop control of a GaAs-based singlet-triplet spin qubit with 99.5% gate fidelity and low leakage. Nat. Commun. 11, 4144 (2020).
- High-fidelity gate set for exchange-coupled singlet-triplet qubits. Phys. Rev. B 101, 155311 (2020).
- Jirovec, D. etĀ al. A singlet-triplet hole spin qubit in planar Ge. Nat. Mater. 20, 1106ā1112 (2021).
- Takeda, K. etĀ al. Optimized electrical control of a Si/SiGe spin qubit in the presence of an induced frequency shift. npj Quantum Inf. 4, 54 (2018).
- Undseth, B. etĀ al. Hotter is easier: Unexpected temperature dependence of spin qubit frequencies. Phys. Rev. X 13, 041015 (2023).
- Undseth, B. etĀ al. Nonlinear response and crosstalk of electrically driven silicon spin qubits. Phys. Rev. Appl. 19, 044078 (2023).
- Current rectification by pauli exclusion in a weakly coupled double quantum dot system. Science 297, 1313ā1317 (2002).
- Qiao, H. etĀ al. Floquet-enhanced spin swaps. Nat. Commun. 12, 2142 (2021).
- Chanrion, E. etĀ al. Charge detection in an array of CMOS quantum dots. Phys. Rev. Appl. 14, 024066 (2020).
- Duan, J. etĀ al. Remote capacitive sensing in two-dimensional quantum-dot arrays. Nano Lett. 20, 7123ā7128 (2020).
- Hsiao, T.Ā K. etĀ al. Exciton transport in a germanium quantum dot ladder. arXiv preprint arXiv:2307.02401 (2023).
- Borsoi, F. etĀ al. Shared control of a 16 semiconductor quantum dot crossbar array. Nat. Nanotechnol. 1ā7 (2023).
- Neyens, S. etĀ al. Probing single electrons across 300 mm spin qubit wafers. arXiv preprint arXiv:2307.04812 (2023).
- Scappucci, G. etĀ al. The germanium quantum information route. Nat. Rev. Mater. 6, 926ā943 (2021).
- A coherent beam splitter for electronic spin states. Science 327, 669ā672 (2010).
- Harnessing the GaAs quantum dot nuclear spin bath for quantum control. Phys. Rev. B 82, 115445 (2010).
- Nichol, J.Ā M. etĀ al. Quenching of dynamic nuclear polarization by spin-orbit coupling in GaAs quantum dots. Nat. Commun. 6, 7682 (2015).
- Jirovec, D. etĀ al. Dynamics of hole singlet-triplet qubits with large gšgitalic_g-factor differences. Phys. Rev. Lett. 128, 126803 (2022).
- All-electrical control of hole singlet-triplet spin qubits at low-leakage points. Phys. Rev. B 104, 195421 (2021).
- Quantum control of hole spin qubits in double quantum dots. Phys. Rev. Appl. 18, 054090 (2022).
- Coherent spināvalley oscillations in silicon. Nature Physics 19, 386ā393 (2023).
- Rooney, J. etĀ al. Gate modulation of the hole singlet-triplet qubit frequency in germanium. arXiv preprint arXiv:2311.10188 (2023).
- Lodari, M. etĀ al. Low percolation density and charge noise with holes in germanium. Mater. Quantum Technol. 1, 011002 (2021).
- Bertrand, B. etĀ al. Quantum manipulation of two-electron spin states in isolated double quantum dots. Phys. Rev. Lett. 115, 096801 (2015).
- Hendrickx, N. etĀ al. A single-hole spin qubit. Nat. Commun. 11, 3478 (2020).
- Martins, F. etĀ al. Noise suppression using symmetric exchange gates in spin qubits. Phys. Rev. Lett. 116, 116801 (2016).
- Reed, M.Ā D. etĀ al. Reduced sensitivity to charge noise in semiconductor spin qubits via symmetric operation. Phys. Rev. Lett. 116, 110402 (2016).
- Hendrickx, N. etĀ al. Sweet-spot operation of a germanium hole spin qubit with highly anisotropic noise sensitivity. arXiv preprint arXiv:2305.13150 (2023).
- Charge-fluctuation-induced dephasing of exchange-coupled spin qubits. Phys. Rev. Lett. 96, 100501 (2006).
- Spin decoherence in a two-qubit CPHASE gate: the critical role of tunneling noise. npj Quantum Inf. 4, 62 (2018).
- Wang, Z. etĀ al. Optimal operation points for ultrafast, highly coherent Ge hole spin-orbit qubits. npj Quantum Inf. 7, 54 (2021).
- Modelling of planar germanium hole qubits in electric and magnetic fields. arXiv preprint arXiv:2208.04795 (2022).
- Massai, L. etĀ al. Impact of interface traps on charge noise, mobility and percolation density in Ge/SiGe heterostructures. arXiv preprint arXiv:2310.05902 (2023).
- Lodari, M. etĀ al. Lightly strained germanium quantum wells with hole mobility exceeding one million. Appl. Phys. Lett. 120 (2022).
- Stehouwer, L.Ā E. etĀ al. Germanium wafers for strained quantum wells with low disorder. Appl. Phys. Lett. 123 (2023).
- Surprises on the way from one-to two-dimensional quantum magnets: The ladder materials. Science 271, 618ā623 (1996).
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