Hyperfine Structure and Nuclear Hyperpolarization Observed in the Bound Exciton Luminescence of Bi Donors in Natural Si

There is a growing interest in bismuth-doped silicon (Si:Bi) as an alternative to the well-studied proposals for silicon-based quantum information processing (QIP) using phosphorus-doped silicon (Si:P). We focus here on the implications of its anomalously strong hyperfine coupling. In particular, we analyze in detail the regime where recent pulsed magnetic resonance experiments have demonstrated the potential for orders of magnitude speedup in quantum gates by exploiting transitions that are electron paramagnetic resonance (EPR) forbidden at high fields. We also present calculations using a phenomenological Markovian master equation, which models the decoherence of the electron spin due to Gaussian temporal magnetic field perturbations. The model quantifies the advantages of certain "optimal working points" identified as the df /dB = 0 regions, where f is the transition frequency, which come in the form of frequency minima and maxima. We show that at such regions, dephasing due to the interaction of the electron spin with a fluctuating magnetic field in the z direction (usually adiabatic) is completely removed.

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“…4 Efficient hyperpolarization of the system (to about 90%) was demonstrated experimentally in Ref. 6.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8] The Si:Bi system is unique in several respects: it is the deepest group V donor with a binding energy of about 71 meV, it has a very large nuclear spin, I = 9/2, it has an exceptionally large hyperfine coupling strength, A/2π = 1.4754 GHz. 209 Bi is the only naturally-occurring isotope.…”

Section: Introductionmentioning

confidence: 99%

Analysis of quantum coherence in bismuth-doped silicon: A system of strongly coupled spin qubits

et al. 2012

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“…The small Bohr radius and bismuth's reduced effective gyromagnetic ratio [7] can make it less susceptible to interface noise at a given implant depth and make bismuth very desirable for quantum logic implementation via magnetic dipolar coupling [11]. Furthermore, bismuth is also the heaviest donor in silicon and thus shows the least ion range straggling during ion implantation, which enables for donor qubit placement with high spatial resolution [12,13].To date, studies of spin resonance properties of bismuth in silicon have been performed with bulk doped natural silicon [7,8,[14][15][16] whereas silicon-28 material is preferable for improved spin coherence properties. Electrical activation of implanted bismuth via thermal anneals has been studied for relatively high implant doses [17][18][19][20][21], and concentrations close to the the metalinsulator transition (N c = 1.7 × 10 19 cm −3 ) [18].…”

mentioning

confidence: 99%

“…To date, studies of spin resonance properties of bismuth in silicon have been performed with bulk doped natural silicon [7,8,[14][15][16] whereas silicon-28 material is preferable for improved spin coherence properties. Electrical activation of implanted bismuth via thermal anneals has been studied for relatively high implant doses [17][18][19][20][21], and concentrations close to the the metalinsulator transition (N c = 1.7 × 10 19 cm −3 ) [18].…”

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confidence: 99%

Electrical activation and electron spin resonance measurements of implanted bismuth in isotopically enriched silicon-28

Weis

Lang

et al. 2012

Applied Physics Letters

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We have performed continuous wave and pulsed electron spin resonance measurements of implanted bismuth donors in isotopically enriched silicon-28. Donors are electrically activated via thermal annealing with minimal diffusion. Damage from bismuth ion implantation is repaired during thermal annealing as evidenced by narrow spin resonance linewidths (Bpp = 12 µT) and long spin coherence times (T2 = 0.7 ms, at temperature T = 8 K). The results qualify ion implanted bismuth as a promising candidate for spin qubit integration in silicon.Electron and nuclear spins of donor atoms in silicon are excellent qubit candidates for quantum information processing [1, 2]. Isotope engineered substrates provide a nuclear spin free host environment, resulting in long electron and nuclear spin coherence times of several seconds [3,4]. Spin properties of donor qubit candidates in silicon have been studied mostly for phosphorous and antimony [3][4][5][6]. Bismuth donors in silicon are unique in exhibiting a relatively large zero field splitting of 7.4 GHz. Thus, they have attracted attention as potential nuclear spin memory and spin qubit candidates [7,8] that could be coupled to superconducting resonators [7,9,10]. Bismuth is the deepest donor in silicon with a binding energy of 70 meV and a corresponding small Bohr radius. The small Bohr radius and bismuth's reduced effective gyromagnetic ratio [7] can make it less susceptible to interface noise at a given implant depth and make bismuth very desirable for quantum logic implementation via magnetic dipolar coupling [11]. Furthermore, bismuth is also the heaviest donor in silicon and thus shows the least ion range straggling during ion implantation, which enables for donor qubit placement with high spatial resolution [12,13].To date, studies of spin resonance properties of bismuth in silicon have been performed with bulk doped natural silicon [7,8,[14][15][16] whereas silicon-28 material is preferable for improved spin coherence properties. Electrical activation of implanted bismuth via thermal anneals has been studied for relatively high implant doses [17][18][19][20][21], and concentrations close to the the metalinsulator transition (N c = 1.7 × 10 19 cm −3 ) [18]. High implant doses ( 1 × 10 14 cm −2 for keV Bi-ions at room temperature) amorphize the silicon lattice [22]. Solid- * Please contact the corresponding author under cdweis@lbl.gov phase epitaxial regrowth (SPER) can be used to prevent diffusion of bismuth atoms and incorporate them on substitutional sites. This can lead to electrically active concentrations well above the low relatively solubility limit of bismuth in silicon (which is, e.g. 2.3 × 10 17 cm −3 at 1150 ℃ [23]). For SPER, thermal anneals at low temperatures, e.g. few minutes at 600 ℃ yield electrical activation levels of up to 90 % [20]. For low implant doses and dopant concentrations, which are desirable for long spin coherence times, no amorphization of the silicon crystal occurs during ion implantation. Thus, the electrical activation levels and annealing ...

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“…The zero-field splitting of the Bi donor level is given by 5A and has been observed by electron spin resonance [20][21][22] and in photoluminescence experiments with many dopants. 23 We consider the sequential transport regime, where the occupation of the donor level fluctuates between q = 0 and q = 1. In the q = 0 state, the nuclear spin interacts only with the external field.…”

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confidence: 99%

Probing a single nuclear spin in a silicon single electron transistor

2012

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We study single electron transport across a single Bi dopant in a Silicon Nanotransistor to assess how the strong hyperfine coupling with the Bi nuclear spin I = 9/2 affects the transport characteristics of the device. In the sequential tunneling regime we find that at, temperatures in the range of 100mK, dI/dV curves reflect the zero field hyperfine splitting as well as its evolution under an applied magnetic field. Our non-equilibrium quantum simulations show that nuclear spins can be partially polarized parallel or antiparallel to the electronic spin just tuning the applied bias. PACS: 73.23.Hk, 31.30.Gs, 74.55.+v, The amazing progress both in the silicon processing technologies and in the miniaturization of silicon based transistors has reached the point where singledopant transistors have been demonstrated.1-7 Whereas this progress has been fueled by the development of classical computing architectures, it might also be used for quantum computing. In this regard, the electronic and nuclear spins of single donors in silicon are very promising building blocks for quantum computing.8-10 Progress along this direction makes it necessary to implement single spin readout schemes both for electronic and nuclear spins. Single electronic spin readout has been demonstrated, both in GaAs quantum dots as well as in P doped Silicon Nanotransistors. 11,12The readout of the quantum state of a single nuclear spin, much more challenging, has been demonstrated for NV centers in diamond taking advantage of single spin optically detected magnetic resonance afforded by the extraordinary properties of that system. 13 Single nuclear spin readout with either optical 14 or a combined electrooptical techniques 15 has been proposed, but remains to be implemented. Here we explore the electrical readout of a single nuclear spin, more suitable for an indirect band-gap host like Si. A preliminary step is to construct a circuit whose transport is affected by the quantum state of the nuclear spin. There is ample experimental evidence of the mutual influence of many nuclear spins and transport electrons in III-V semiconductor quantum dots in the single electron transport regime. [16][17][18][19] In particular, Kobayashi et al. have reported hysteresis in the dI/dV upon application of magnetic fields, reflecting the realization of different ensemble of nuclear states coupled to the electronic spin via hyperfine coupling. 19Here we propose a device where a single nuclear spin is probed in single electron transport. We model the single electron transport in a silicon nanotransistor such that, in the active region, transport takes place through a single Bi dopant, see Fig. 1. We show that, at sufficiently low temperatures, the dI/dV curves of this device probe the hyperfine structure of the dopant level. In turn, the occupations of the nuclear spin states are affected by the transport electrons. Whereas single dopant transistors have been demonstrated for single P, As and B, in Si, 3,4,6,12 we choose Bi because it has a much larger hyperfine spl...

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Hyperfine Structure and Nuclear Hyperpolarization Observed in the Bound Exciton Luminescence of Bi Donors in Natural Si

Cited by 41 publications

References 18 publications

Analysis of quantum coherence in bismuth-doped silicon: A system of strongly coupled spin qubits

Analysis of quantum coherence in bismuth-doped silicon: A system of strongly coupled spin qubits

Electrical activation and electron spin resonance measurements of implanted bismuth in isotopically enriched silicon-28

Probing a single nuclear spin in a silicon single electron transistor

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