Nanoscale broadband transmission lines for spin qubit control

Dehollain, Juan Pablo; Pla, Jarryd; Siew, Eugene; Tan, Kuan Yen; Dzurak, A. S.; Morello, Andrea

doi:10.1088/0957-4484/24/1/015202

Cited by 68 publications

(72 citation statements)

References 29 publications

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“…Spin control was achieved through microwave and RF excitations generated by an arXiv:1408.1347v1 [cond-mat.mes-hall] 6 Aug 2014 on-chip broadband transmission line [17]. The 31 P donor in silicon represents a two-qubit system, with an electron spin (S = 1/2) bound at cryogenic temperatures to a nuclear spin (I = 1/2).…”

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confidence: 99%

Coherent Control of a SingleSi29Nuclear Spin Qubit

et al. 2014

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Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV materials, the spin-bearing nuclei are sufficiently rare that it is possible to identify and control individual host nuclear spins. This work presents the first experimental detection and manipulation of a single 29 Si nuclear spin. The quantum non-demolition (QND) single-shot readout of the spin is demonstrated, and a Hahn echo measurement reveals a coherence time of T2 = 6.3(7) ms -in excellent agreement with bulk experiments. Atomistic modeling combined with extracted experimental parameters provides possible lattice sites for the 29 Si atom under investigation. These results demonstrate that single 29 Si nuclear spins could serve as a valuable resource in a silicon spin-based quantum computer.The presence of non-zero nuclear spins in a host crystal lattice is known to induce decoherence in a central spin qubit through mechanisms such as spectral diffusion [1]. This "nuclear bath" is the primary source of decoherence for 31 P electron and nuclear spin qubits in silicon [2,3], nitrogen-vacancy (NV) centers in diamond [4], as well as for GaAs-based quantum dot spin qubits [5,6]. However, for semiconductors composed of majority spin-zero isotopes (such as silicon and carbon), the low abundance of spin-carrying nuclei allows to resolve the hyperfine couplings of individual nuclei with a central electronic spin, permitting the detection and manipulation of single nuclear spins. This has led to the demonstration of a quantum register for the spin of a NV center in diamond, where the electronic spin state can be stored in individual nuclei [7] and read out in single shot [8]. Quantum error correction protocols have been implemented within these nuclear spin registers [9,10], showing their potential to implement surface-code based quantum computing architectures [11]. Natural silicon contains a 4.7% abundance of the spin-carrying (I = 1/2) 29 Si isotope which, in combination with a localized electron spin, could in principle be used as quantum register or ancilla qubit equivalently to 13 C in NV-diamond. In addition, the 29 Si nuclear spin has itself been championed as a quantum bit in an "allsilicon" quantum computer [12,13].Here we present the first experimental demonstration of single-shot readout, coherent control, and measurement of the coherence properties of an individual 29 Si nuclear spin in natural Si. All measurements were performed with a magnetic field B 0 = 1.77 T, in a dilution refrigerator with electron temperature T el ≈ 250 mK. This work follows from previous experiments where the electron [2] and nuclear [3] spins of a single 31 P donor were detected using a compact nanoscale device [14] consisting of ion-implanted phosphorus donors [15], tunnel-coupled to a silicon MOS single- electron transistor (SET) [16]. Spin control was achieved through microwave and RF excitations generated by an arXiv:1408.1347v1 [cond-mat.mes-hall]

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confidence: 99%

Coherent Control of a SingleSi29Nuclear Spin Qubit

et al. 2014

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“…A microwave pulse of power P MW ¼ 2 dBm at the source (the coaxial cable connecting the source to the device provides a further 30 dB attenuation) and duration T P ¼ 50 ls was then applied to an adjacent broadband microwave antenna. 24 Since T P is much longer than the typical dephasing time T ? 2 % 55 ns for 31 P in natural silicon, 7 the electron spin is left in a random orientation when the applied frequency is in resonance with the j #i $ j "i ESR transition or remains in the j #i eigenstate when off-resonance.…”

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confidence: 99%

High-fidelity adiabatic inversion of a ³¹P electron spin qubit in natural silicon

et al. 2014

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The main limitation to the high-fidelity quantum control of spins in semiconductors is the presence of strongly fluctuating fields arising from the nuclear spin bath of the host material. We demonstrate here a substantial improvement in single-qubit inversion fidelities for an electron spin qubit bound to a 31 P atom in natural silicon, by applying adiabatic sweeps instead of narrow-band pulses. We achieve an inversion fidelity of 97%, and we observe signatures in the spin resonance spectra and the spin coherence time that are consistent with the presence of an additional exchange-coupled donor. This work highlights the effectiveness of simple adiabatic inversion techniques for spin control in fluctuating environments. P donor electron 7 and nuclear 8 spins in silicon. In any III-V semiconductor, as well as in natural Si, the fluctuating nuclear spin environment is the main factor limiting spin coherence times 9,10 and, importantly, the fidelity of quantum gate operations, with typical fidelities in the range of 55%-75%. 4,7 This is insufficient for fault-tolerant qubit operations, which require fidelities in excess of 99% even in the most optimistic schemes.11 Group IV semiconductors such as Si and C possess spin-zero nuclear isotopes, which can be artificially enriched to create a nearly spin-free environment for spin qubits. Indeed 28 Si has been termed a "semiconductor vacuum" 12 for this reason. Ensemble spin resonance of 31 P donors in isotopically pure 28 Si has shown extraordinarily long coherence times, T 2e % 10 s for the electron 13 and T 2n % 3 h for the nucleus, 14 and it is certainly an exciting prospect to adopt isotopically pure substrates for nanoscale qubit devices. However, the production of nuclear spin-zero environments in isotopically purified semiconductors other than silicon is relatively undeveloped 15 or impossible because of the lack of suitable isotopes. Therefore, methods to maximize qubit control fidelities in the presence of a nuclear spin environment will remain important.In this Letter, we present how adiabatic frequency sweeps can be utilized to control the spin of an electron bound to a single 31 P donor with high-fidelity, in spite of the fluctuating nuclear spins from the 4.7% 29 Si (spin 1/2) in natural silicon. For an inhomogeneously broadened electron spin resonance (ESR) transition at $36 GHz with a linewidth of $12 MHz, we achieved an average electron spin inversion fidelity as high as F I ¼ 97 6 2%, insensitive to fluctuations of the background nuclear field. The method of adiabatic passage has been widely applied in nuclear magnetic resonance 16 and to some extent also in ESR. 17 Recent progress in high-frequency electronics and the very active research field of spin-based quantum computation have reignited the interest in this topic, with applications as ultra-wideband inversion, 18 geometric phase gates, 19 and even the inversion of single electron spins in diamond. 20,21 Our single qubit, however, is operated at much higher frequencies (36 GHz in the present work) t...

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“…Heating due to ESR pulses can be mitigated by using cavities to confine the microwave modes [98,152,153], but this presents other challenges for bringing metal electrodes to the dots. Ongoing work in superconducting qubits for combining complex electromagnetic environments with sub-Kelvin temperatures makes us optimistic that engineering solutions are possible here as well [12,88,154,155].…”

Section: Discussionmentioning

confidence: 99%

“…[27,31] and employing a microwave electron-spin resonance (ESR) antenna as in Ref. [88]. In this section, we first present the chosen methods for spin initialization, control, and measurement supported by this architecture.…”

Section: Controlling Spins In a Linear Arraymentioning

confidence: 99%

“…However, existing experimental implementations of cryogenic ESR give strong encouragement that these pulses can be achieved with high fidelity. Through the use of an on-chip transmission line [88], ESR control of single electron spins in SiMOS devices has been demonstrated with benchmarked control fidelity of as high as 99.6% [40,51]; another experiment with a micromagnet in Si=SiGe dots realized 99% fidelity [52]. However, as the number of electron spins in the device increases, frequency crowding becomes a notable issue, so the global ESR scheme introduced in the previous section would have all spins controlled simultaneously by a common ESR transmission line.…”

Section: B Experimental State Of the Art And Simulated Performance Imentioning

confidence: 99%

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Logical Qubit in a Linear Array of Semiconductor Quantum Dots

et al. 2018

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We design a logical qubit consisting of a linear array of quantum dots, we analyze error correction for this linear architecture, and we propose a sequence of experiments to demonstrate components of the logical qubit on near-term devices. To avoid the difficulty of fully controlling a two-dimensional array of dots, we adapt spin control and error correction to a one-dimensional line of silicon quantum dots. Control speed and efficiency are maintained via a scheme in which electron spin states are controlled globally using broadband microwave pulses for magnetic resonance, while two-qubit gates are provided by local electrical control of the exchange interaction between neighboring dots. Error correction with two-, three-, and fourqubit codes is adapted to a linear chain of qubits with nearest-neighbor gates. We estimate an error correction threshold of 10 −4 . Furthermore, we describe a sequence of experiments to validate the methods on near-term devices starting from four coupled dots.

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Nanoscale broadband transmission lines for spin qubit control

Cited by 68 publications

References 29 publications

Coherent Control of a SingleSi29Nuclear Spin Qubit

Coherent Control of a SingleSi29Nuclear Spin Qubit

High-fidelity adiabatic inversion of a ³¹P electron spin qubit in natural silicon

Logical Qubit in a Linear Array of Semiconductor Quantum Dots

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Nanoscale broadband transmission lines for spin qubit control

Cited by 68 publications

References 29 publications

Coherent Control of a SingleSi29Nuclear Spin Qubit

Coherent Control of a SingleSi29Nuclear Spin Qubit

High-fidelity adiabatic inversion of a 31P electron spin qubit in natural silicon

Logical Qubit in a Linear Array of Semiconductor Quantum Dots

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High-fidelity adiabatic inversion of a ³¹P electron spin qubit in natural silicon