{"id":57489,"date":"2023-05-02T16:08:30","date_gmt":"2023-05-02T14:08:30","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=57489"},"modified":"2023-05-02T16:08:30","modified_gmt":"2023-05-02T14:08:30","slug":"these-baker-shalak-modeling-of-quantum-bit-in-silicon-technology","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/agenda\/these-baker-shalak-modeling-of-quantum-bit-in-silicon-technology.html","title":{"rendered":"THESE :Baker SHALAK \u2013 \u00ab Modeling of Quantum Bit in Silicon Technology \u00bb"},"content":{"rendered":"<div id='layer_slider_1'  class='avia-layerslider main_color avia-shadow  avia-builder-el-0  el_before_av_heading  avia-builder-el-first  container_wrap sidebar_right'  style='height: 261px;'  ><div id=\"layerslider_58_q2ofi5yqh87g\" data-ls-slug=\"homepageslider\" class=\"ls-wp-container fitvidsignore ls-selectable\" style=\"width:1140px;height:260px;margin:0 auto;margin-bottom: 0px;\"><div class=\"ls-slide\" 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0;\npadding-bottom:4px;\n}\nbody .av-special-heading.av-lh6ch8g0-ccac9b2842e18192abeca09d2d3b0a93 .av-special-heading-tag .heading-char{\nfont-size:25px;\n}\n.av-special-heading.av-lh6ch8g0-ccac9b2842e18192abeca09d2d3b0a93 .av-subheading{\nfont-size:15px;\n}\n<\/style>\n<div  class='av-special-heading av-lh6ch8g0-ccac9b2842e18192abeca09d2d3b0a93 av-special-heading-h2  avia-builder-el-1  el_after_av_layerslider  el_before_av_hr  avia-builder-el-first'><h2 class='av-special-heading-tag'  itemprop=\"headline\"  >THESE :Baker SHALAK \u2013 \u00ab Modeling of Quantum Bit in Silicon Technology \u00bb <\/h2><div class=\"special-heading-border\"><div class=\"special-heading-inner-border\"><\/div><\/div><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-18u73nj-dad6a947580930e400fc42ba200e80f1\">\n#top .hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1{\nmargin-top:5px;\nmargin-bottom:5px;\n}\n.hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1 .hr-inner{\nwidth:100%;\n}\n<\/style>\n<div  class='hr av-18u73nj-dad6a947580930e400fc42ba200e80f1 hr-custom  avia-builder-el-2  el_after_av_heading  el_before_av_textblock  hr-left hr-icon-no'><span class='hr-inner inner-border-av-border-thin'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<section  class='av_textblock_section av-jriy64i8-2f4600354c0449b610997916bbd9b6bc'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" >\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-13ewzjw-68e036126b913e5028f77311dc66b825\">\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825{\ncolor:#bfbfbf;\nborder-color:#bfbfbf;\n}\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825 .av-icon-char{\nfont-size:60px;\nline-height:60px;\n}\n<\/style>\n<span  class='av_font_icon av-13ewzjw-68e036126b913e5028f77311dc66b825 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue8c9' data-av_iconfont='entypo-fontello' ><\/span><\/span>\n<p>THESE :Baker SHALAK \u2013 \u00ab Modeling of Quantum Bit in Silicon Technology \u00bb<\/p>\n<p>Soutenance : 10 Mai 2023<\/p>\n<p><strong>Mercredi 10 Mai 2023 \u00e0 10h<br \/>\n<\/strong>Amphitheatre of the IEMN-Laboratoire central - Villeneuve d'Ascq<\/p>\n<\/div><\/section>\n<section  class='av_textblock_section av-jtefqx33-628129dba2299b2ecd65ebfc92eac29d'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div  class='hr av-kjh3zw-4dff888f744b728a1aca9b3a0971493a hr-default  avia-builder-el-6  avia-builder-el-no-sibling'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<h5><strong><span style=\"color: #800000;\">Jury :<\/span><\/strong><\/h5>\n<div>\n<p>Monsieur Marco PALA, \u00a0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 HDR, DR CNRS, C2N, Rapporteur<br \/>\nMonsieur Nicolas CAVASSILAS, \u00a0\u00a0\u00a0 HDR, Professeur \u00e0 Aix-Marseille Universit\u00e9, IM2NP, Rapporteur<br \/>\nMadame Val\u00e9rie VALLET HDR, \u00a0 \u00a0\u00a0 DR CNRS, PhLam, Examinatrice<br \/>\nMonsieur Romain MAURAND, \u00a0 \u00a0 \u00a0 HDR, LaTEQS, CEA Grenoble, Examinateur<br \/>\nMonsieur Yann-Michel NIQUET, \u00a0\u00a0 HDR, IRIG, CEA Grenoble, Examinateur<br \/>\nChristophe DELERUE,\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 DR CNRS, HDR, IEMN, Directeur de la th\u00e8se<\/p>\n<\/div>\n<h5>Summary:<\/h5>\n<p>Les sources de bruit sont l\u2019un des facteurs critiques qui d\u00e9terminent la performance des qubits dans les applications d\u2019informatique quantique. Les sources de bruit se r\u00e9f\u00e8rent \u00e0 tous les facteurs externes qui peuvent provoquer des erreurs ou une d\u00e9coh\u00e9rence dans un qubit. Dans cette th\u00e8se, nous avons simul\u00e9 ces effets dans le cas d\u2019un qubit de spin \u00e0 trou dans la technologie du silicium sur isolant (SOI).<\/p>\n<p>Les fluctuations de charge sont l\u2019une des principales sources de bruit dans les qubits de spin \u00e0 trous. La pr\u00e9sence de charges mobiles peut introduire des fluctuations dans le champ \u00e9lectrique autour du trou. Les fluctuateurs de charge peuvent provenir d\u2019impuret\u00e9s ou de d\u00e9fauts dans les couches d\u2019oxyde \u00e0 proximit\u00e9 des r\u00e9gions de silicium. Ils peuvent induire des changements al\u00e9atoires dans les niveaux d\u2019\u00e9nergie, les fonctions d\u2019onde et les facteurs $g$ du spin du trou, provoquant des erreurs ou une d\u00e9coh\u00e9rence dans le qubit.<\/p>\n<p>Il est donc essentiel d\u2019\u00e9tudier l\u2019impact des fluctuateurs de charge sur le qubit de spin \u00e0 trous. Nous simulons un point quantique confinant un seul trou. Le confinement est d\u00e9fini par des portes \u00e9lectrostatiques sur un canal de nanofil de silicium. Notre objectif est de d\u00e9crire le qubit de la mani\u00e8re la plus r\u00e9aliste possible par rapport aux technologies qui ont \u00e9t\u00e9 r\u00e9cemment d\u00e9velopp\u00e9es et caract\u00e9ris\u00e9es. Notre simulation prend en compte la relaxation et le d\u00e9phasage du spin du trou dans le temps en combinant les \u00e9quations de Poisson et de Schroedinger d\u00e9pendantes du temps pour mod\u00e9liser un signal t\u00e9l\u00e9graphique al\u00e9atoire classique. Notre approche est capable de d\u00e9crire les effets combin\u00e9s des champs \u00e9lectriques fluctuants et du couplage spin-orbite sur la dynamique du spin, sans aucun param\u00e8tre libre.<\/p>\n<p>Nous montrons que le mod\u00e8le \u00e0 deux niveaux bien connu d\u00e9crit efficacement le temps de d\u00e9phasage $T_2$ sur une large gamme de fr\u00e9quences $\\nu$ du signal t\u00e9l\u00e9graphique. Lorsque $\\nu$ est faible, la d\u00e9coh\u00e9rence est d\u00e9termin\u00e9e par le comportement \u00e0 court terme de la phase de pr\u00e9cession du spin qui est alors caract\u00e9ris\u00e9e par une distribution non gaussienne, la coh\u00e9rence de la phase est perdue d\u00e8s que le fluctuateur change d\u2019\u00e9tat. La description gaussienne n\u2019est pr\u00e9cise qu\u2019au-del\u00e0 d\u2019une fr\u00e9quence seuil $\\om\u00e9ga_{th}$, lorsque le syst\u00e8me \u00e0 deux niveaux r\u00e9pond \u00e0 la distribution statistique des \u00e9tats du fluctuateur. Le temps de d\u00e9phasage $T_2$ \u00e0 cette fr\u00e9quence seuil peut \u00eatre significativement augment\u00e9 en ajustant l\u2019orientation du champ magn\u00e9tique et les potentiels de grille le long des lignes \u00ab\u00a0douces\u00a0\u00bb. Cependant, nous montrons que $T_2$ ne peut pas tendre vers l\u2019infini pour des raisons qui sont discut\u00e9es. L\u2019existence de points \u00ab\u00a0doux\u00a0\u00bb est maintenant un fait \u00e9tabli exp\u00e9rimentalement. Les simulations montrent \u00e9galement que le temps de relaxation du spin $T_1$ ne peut pas \u00eatre d\u00e9crit avec pr\u00e9cision par le mod\u00e8le \u00e0 deux niveaux, car le couplage avec des niveaux de trous de plus haute \u00e9nergie a un impact consid\u00e9rable sur la dynamique du spin.<\/p>\n<p>Nous \u00e9tudions \u00e9galement les processus de d\u00e9coh\u00e9rence dans le m\u00eame qubit de spin \u00e0 trous en utilisant la th\u00e9orie Bloch-Redfield. Nous montrons que cette th\u00e9orie fonctionne bien \u00e0 haute fr\u00e9quence $\\nu$, lorsque la dynamique du spin du trou est lente compar\u00e9e aux fluctuations de son environnement. Les limites de la th\u00e9orie de Bloch-Redfield \u00e0 basse fr\u00e9quence sont identifi\u00e9es.<\/p>\n<h5>Abstract:<\/h5>\n<p>Noise sources are one of the critical factors that determine the performance of qubits in quantum computing applications. Noise sources refer to any external factors that can cause errors or decoherence in a qubit. In this thesis, we have simulated these effects in the case of a hole spin qubit in Silicon-On-Insulator (SOI) technology.<\/p>\n<p>Charge fluctuators are one of the major sources of noise in hole spin qubits. The presence of moving charges can introduce fluctuations in the electric field around the hole. Charge fluctuators may arise from impurities or defects in the oxide layers in the vicinity of silicon regions. They can induce random changes in the energy levels, wavefunctions and $g$-factors of the hole spin, causing errors or decoherence in the qubit.<\/p>\n<p>This makes it essential to study the impact of charge fluctuators on hole spin qubit. We simulate a quantum dot confining a single hole. The confinement is defined by electrostatic gates on a silicon nanowire channel. Our goal is to describe the qubit as realistically as possible compared to technologies which were recently developed and characterized. Our simulation takes into account the relaxation and the dephasing of the hole spin over time by combining Poisson and time-dependent Schroedinger equations to model a classical random telegraph signal. Our approach is able to describe the combined effects of fluctuating electric fields and spin-orbit coupling on the spin dynamics, without any free parameter.<\/p>\n<p>We show that the well-known two-level model effectively describes the dephasing time $T_2$ over a broad range of frequencies $\\nu$ of the telegraph signal. When $\\nu$ is low, the decoherence is determined by the short time behavior of the spin precession phase which is then characterized by a non-Gaussian distribution, the coherence of the phase is lost as soon as the fluctuator changes state. The Gaussian description is only accurate above a threshold frequency $\\omega_{th}$, when the two-level system responds to the statistical distribution of the fluctuator states. The dephasing time $T_2$ at this threshold frequency can be significantly increased by adjusting the magnetic field orientation and gate potentials along \u00ab\u00a0sweet\u00a0\u00bb lines. However, we show that $T_2$ cannot tend to infinity for reason which are discussed. The existence of \u00ab\u00a0sweet\u00a0\u00bb points is now an experimentally established fact. The simulations also show that the spin relaxation time $T_1$ cannot be accurately described by the two-level model as the coupling to higher-energy hole levels greatly impacts the spin dynamics.<\/p>\n<p>We also study decoherence processes in the same hole spin qubit using the Bloch-Redfield theory. We show that this theory works well at high frequency $\\nu$, when the dynamics of the hole spin is slow compared to the fluctuations of its environment. Limits of the Bloch-Redfield theory at low frequency are identified.<\/p>\n<\/div><\/section>","protected":false},"excerpt":{"rendered":"","protected":false},"author":20,"featured_media":57490,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[65,87,84],"tags":[],"class_list":["post-57489","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-agenda","category-agenda-en","category-agenda-en-en"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/57489","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=57489"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/57489\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/57490"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=57489"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=57489"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=57489"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}