Atomistic compositional details and their importance for spin qubits in isotope-purified silicon-germanium quantum wells

• URL: http://arxiv.org/abs/2405.19974v1
• Date: Thu, 30 May 2024 11:57:18 GMT
• Title: Atomistic compositional details and their importance for spin qubits in isotope-purified silicon-germanium quantum wells
• Authors: Jan Klos, Jan Tröger, Jens Keutgen, Merritt P. Losert, Helge Riemann, Nikolay V. Abrosimov, Joachim Knoch, Hartmut Bracht, Susan N. Coppersmith, Mark Friesen, Oana Cojocaru-Mirédin, Lars R. Schreiber, Dominique Bougeard,
• Abstract summary: Isotope composition depth profiles in a SiGe28$Si/SiGe heterostructure are analyzed. Spin-echo dephasing times and valley energy splittings have been observed for single spin qubits in this quantum well (QW) heterostructure.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Understanding crystal characteristics down to the atomistic level increasingly emerges as a crucial insight for creating solid state platforms for qubits with reproducible and homogeneous properties. Here, isotope composition depth profiles in a SiGe/$^{28}$Si/SiGe heterostructure are analyzed with atom probe tomography (APT) and time-of-flight secondary-ion mass spectrometry. Spin-echo dephasing times $T_2^{echo}=128 \mu s$ and valley energy splittings around $200 \mu eV$ have been observed for single spin qubits in this quantum well (QW) heterostructure, pointing towards the suppression of qubit decoherence through hyperfine interaction or via scattering between valley states. The concentration of nuclear spin-carrying $^{29}$Si is 50 ppm in the $^{28}$Si QW. APT allows to uncover that both the top SiGe/$^{28}$Si and the bottom $^{28}$Si/SiGe interfaces of the QW are shaped by epitaxial growth front segregation signatures on a few monolayer scale. A subsequent thermal treatment broadens the top interface by about two monolayers, while the width of the bottom interface remains unchanged. Using a tight-binding model including SiGe alloy disorder, these experimental results suggest that the combination of the slightly thermally broadened top interface and of a minimal Ge concentration of $0.3 \%$ in the QW, resulting from segregation, is instrumental for the observed large valley splitting. Minimal Ge additions $< 1 \%$, which get more likely in thin QWs, will hence support high valley splitting without compromising coherence times. At the same time, taking thermal treatments during device processing as well as the occurrence of crystal growth characteristics into account seems important for the design of reproducible qubit properties.

Related papers

• (111) Si spin qubits constructed on L point of band structure [0.0]
  Si spin qubits have state-of-the-art miniaturization, integration, and variation-reduction-technologies. New measures are proposed to address issues of relaxation and decoherence time, stabilization of valley-splitting control, and reduction of variation caused by the roughness of the interface. It is hoped that prototype silicon spin qubits constructed on (111) Si crystals will be developed and that the proposed device structure will help implement quantum computers based on Si devices.
  arXiv  Detail & Related papers  (2025-01-23T10:46:35Z)
• Ancilla quantum measurements on interacting chains: Sensitivity of entanglement dynamics to the type and concentration of detectors [46.76612530830571]
  We consider a quantum many-body lattice system that is coupled to ancillary degrees of freedom (detectors'') We explore the dynamics of density and of entanglement entropy in the chain, for various values of $rho_a$ and $M$.
  arXiv  Detail & Related papers  (2023-11-21T21:41:11Z)
• Microwave-based quantum control and coherence protection of tin-vacancy spin qubits in a strain-tuned diamond membrane heterostructure [54.501132156894435]
  Tin-vacancy center (SnV) in diamond is a promising spin-photon interface with desirable optical and spin properties at 1.7 K. We introduce a new platform that overcomes these challenges - SnV centers in uniformly strained thin diamond membranes. The presence of crystal strain suppresses temperature dependent dephasing processes, leading to a considerable improvement of the coherence time up to 223 $mu$s at 4 K.
  arXiv  Detail & Related papers  (2023-07-21T21:40:21Z)
• Nuclear Spin-Depleted, Isotopically Enriched 70Ge/28Si70Ge Quantum Wells [0.0]
  This work demonstrates the epitaxial growth of $text73$Ge-depleted isotopically enriched $text70$Ge/SiGe quantum wells. The measured average distance between nuclear spins reaches 3-4 nm in $text70$Ge/$text28$Si$text70$Ge, which is an order of magnitude larger than in natural Ge/SiGe heterostructures.
  arXiv  Detail & Related papers  (2023-06-06T22:53:30Z)
• Full counting statistics of interacting lattice gases after an expansion: The role of the condensate depletion in the many-body coherence [55.41644538483948]
  We study the full counting statistics (FCS) of quantum gases in samples of thousands of interacting bosons. FCS reveals the many-body coherence from which we characterize iconic states of interacting lattice bosons.
  arXiv  Detail & Related papers  (2022-07-28T13:21:57Z)
• Prolonged orbital relaxation by locally modified phonon density of states for SiV$^-$ center in nanodiamonds [45.82374977939355]
  Coherent quantum systems are a key resource for emerging quantum technology. A novel method is presented to prolong the orbital relaxation with a locally modified phonon density of states.
  arXiv  Detail & Related papers  (2021-07-30T14:14:26Z)
• Enhanced coherence of all-nitride superconducting qubits epitaxially grown on silicon substrate [2.3180219011095327]
  We develop superconducting qubits based on NbN/AlN/NbN epitaxial Josephson junctions on silicon substrates. The all-nitride qubits have great advantages such as chemical stability against oxidation.
  arXiv  Detail & Related papers  (2021-03-13T13:03:17Z)
• Mesoscopic quantum superposition states of weakly-coupled matter-wave solitons [58.720142291102135]
  We establish quantum features of an atomic soliton Josephson junction (SJJ) device. We show that the SJJ-model in quantum domain exhibits unusual features due to its effective nonlinear strength proportional to the square of total particle number. We have shown that the obtained quantum state is more resistant to few particle losses from the condensates if tiny components of entangled Fock states are present.
  arXiv  Detail & Related papers  (2020-11-26T09:26:19Z)
• Deterministic Single Ion Implantation with 99.87% Confidence for Scalable Donor-Qubit Arrays in Silicon [44.62475518267084]
  Group-V-donor spins are attractive qubits for large-scale quantum computer devices. Group-V-donor spins implanted in an isotopically purified $28$Si crystal make them attractive qubits. We demonstrate the implantation of single low-energy (14 keV) P$+$ ions with an unprecedented $99.87pm0.02$% confidence.
  arXiv  Detail & Related papers  (2020-09-07T05:23:07Z)
• Gapless quantum spin liquid and global phase diagram of the spin-1/2 $J_1$-$J_2$ square antiferromagnetic Heisenberg model [1.2728971015881008]
  We show that the intermediate nonmagnetic phase is a gapless quantum spin liquid (QSL), whose spin-spin and dimer-dimer correlations both decay with a power law behavior. We make the first detailed comparison between the results of PEPS and the well-established density matrix renormalization group (DMRG) method through one-to-one direct benchmark for small system sizes.
  arXiv  Detail & Related papers  (2020-09-03T17:39:06Z)
• Spectral and spatial isolation of single WSe$_2$ quantum emitters using hexagonal boron nitride wrinkles [1.037769583357224]
  We create spatially and spectrally isolated quantum emitters from WSe$$ monolayers with few or no sources of emission. We show that a bilayer of hexagonal boron nitride (hBN) and WSe$$ placed on a nano substrate can be used to create and shape wrinkles that communicate local strain to the WSe$$$. We compare quantum emitters created directly on top of substrate features with quantum emitters forming along wrinkles and find that the spectra of the latter consist of mainly a single peak and a low background fluorescence.
  arXiv  Detail & Related papers  (2020-05-14T14:31:38Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.