著者は、テクニカルサポートにマイケルLacerteに感謝します。 MP-L。財政支援のための自然らテクノロジーズ（FRQNT） - 先端研究（CIFAR）、自然科学とカナダの工学研究評議会（NSERC）、イノベーションのためのカナダの財団（CFI）とフォン·ド·ルシェルシュケベックのためのカナダの研究所を認めるものです。ここで紹介するデバイスはNanoQuébecによって部分的に資金提供CRN2とIMDQ施設で製造されました。たGaAs / AlGaAs系基板は国立研究評議会カナダにおける微細構造科学研究所からZR Wasilewskiによって作製した。 JCLとCB-O。財政支援のためのCRSNGとFRQNTを認める。

<ol>
	<li>Shor, P. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polynomial-time+algorithms+for+prime+factorization+and+discrete+logarithms+on+a+quantum+computer.">Polynomial-time algorithms for prime factorization and discrete logarithms on a quantum computer.</a> SIAM J. Sci. Comput. 26 (5), 1484-1509 (1997).</li><li>Bj&#246;rk, M. T., Thelander, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Few-Electron+Quantum+Dots+in+Nanowires.">Few-Electron Quantum Dots in Nanowires.</a> Nano Lett. 4 (9), 1621-1625 (2004).</li><li>Dekker, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+Nanotubes+as+Molecular+Quantum+Wires.">Carbon Nanotubes as Molecular Quantum Wires.</a> Phys. Today. 52 (5), 22-28 (1999).</li><li>Klein, D. L., McEuen, P. L., Bown Katari, J. E., Roth, R., Alivisatos, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Approach+to+Electrical+Studies+of+Single+Nanocrystals.">An Approach to Electrical Studies of Single Nanocrystals.</a> Appl. Phys. Lett. 68 (18), 2574-2576 (1996).</li><li>Kouwenhoven, L. P., Oosterkamp, T. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Excitation+Spectra+in+Circular+Few-Electron+Quantum+Dots.">Excitation Spectra in Circular Few-Electron Quantum Dots.</a> Science. 278 (5344), 1788-1792 (1997).</li><li>Ciorga, M., Sachrajda, A. S. Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Addition+Spectrum+of+a+Lateral+Dot+from+Coulomb+and+Spin-Blockade+Spectroscopy.">Addition Spectrum of a Lateral Dot from Coulomb and Spin-Blockade Spectroscopy.</a> Phys. Rev. B. 61 (24), R16315-R16318 (2000).</li><li>Baca, A. G., Ashby, C. I. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fabrication of GaAs Devices. , 350 (2005).</li><li>Barthel, C., Reilly, D. J., Marcus, C. M., Hanson, M. P., Gossard, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+Single-Shot+Measurement+of+a+Singlet-Triplet+Qubit.">Rapid Single-Shot Measurement of a Singlet-Triplet Qubit.</a> Phys. Rev. Lett. 103 (16), 160503 (2009).</li><li>S, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Survey+of+Ohmic+Contacts+to+III-V+Compound+Semiconductors.">A Survey of Ohmic Contacts to III-V Compound Semiconductors.</a> Thin Solid Films. 308, 599-606 (1997).</li><li>Lim, W. H., Huebl, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrostatically+Defined+Few-Electron+Double+Quantum+Dot+in+Silicon.">Electrostatically Defined Few-Electron Double Quantum Dot in Silicon.</a> Appl. Phys. Lett. 94 (17), 173502 (2009).</li><li>Elzerman, J. M., Hanson, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Few-Electron+Quantum+Dot+Circuit+with+Integrated+Charge+Read+Out.">Few-Electron Quantum Dot Circuit with Integrated Charge Read Out.</a> Phys. Rev. B. 67 (16), 161308 (2003).</li><li>Johnson, A. C., Petta, J. R., Marcus, C. M., Hanson, M. P., Gossard, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Singlet-Triplet+Spin+Blockade+and+Charge+Sensing+in+a+Few-Electron+Double+Quantum+Dot.">Singlet-Triplet Spin Blockade and Charge Sensing in a Few-Electron Double Quantum Dot.</a> Phys. Rev. B. 72 (16), 165308 (2005).</li><li>Hanson, R., Kouwenhoven, L. P., Petta, J. R., Tarucha, S., Vandersypen, L. M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spins+in+Few-Electron+Quantum+Dots.">Spins in Few-Electron Quantum Dots.</a> Rev. Mod. Phys. 79 (4), 1217-1265 (2007).</li><li>Long, A. R., Pioro-Ladri&#232;re, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Origin+of+Switching+Noise+in+GaAs/AlGaAs+Lateral+Gated+Devices.">The Origin of Switching Noise in GaAs/AlGaAs Lateral Gated Devices.</a> Physica E Low Dimens. Syst. Nanostruct. 34 (1-2), 553-556 (2006).</li><li>Koppens, F. H. L., Buizert, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Driven+Coherent+Oscillations+of+a+Single+Electron+Spin+in+a+Quantum+Dot.">Driven Coherent Oscillations of a Single Electron Spin in a Quantum Dot.</a> Nature. 442 (7104), 766-771 (2006).</li><li>Foletti, S., Bluhm, H., Mahalu, D., Umansky, V., Yakobi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Universal+Quantum+Control+of+Two-Electron+Spin+Quantum+Bits+Using+Dynamic+Nuclear+Polarization.">Universal Quantum Control of Two-Electron Spin Quantum Bits Using Dynamic Nuclear Polarization.</a> Nat. Phys. 5 (12), 903-908 (2009).</li><li>Petta, J. R., Lu, H., Gossard, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Coherent+Beam+Splitter+for+Electronic+Spin+States.">A Coherent Beam Splitter for Electronic Spin States.</a> Science. 327 (5966), 669-672 (2010).</li><li>Shulman, M. D., Dial, O. E., Harvey, S. P., Bluhm, H., Umansky, V., Yacoby, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Demonstration+of+Entanglement+of+Electrostatically+Coupled+Singlet-Triplet+Qubits.">Demonstration of Entanglement of Electrostatically Coupled Singlet-Triplet Qubits.</a> Science. 336 (6078), 202-205 (2012).</li><li>Khaetskii, A. V., Loss, D., Glazman, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+Spin+Decoherence+in+Quantum+Dots+Due+to+Interaction+with+Nuclei.">Electron Spin Decoherence in Quantum Dots Due to Interaction with Nuclei.</a> Phys. Rev. Lett. 88 (18), 186802 (2002).</li><li>Sakr, M. R., Jiang, H. W., Yablonovitch, E., Croke, E. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+characterization+of+electrostatic+Si/SiGe+Quantum+Dots+with+an+Integrated+Read-Out+Channel.">Fabrication and characterization of electrostatic Si/SiGe Quantum Dots with an Integrated Read-Out Channel.</a> Appl. Phys. Lett. 87 (22), 223104 (2005).</li><li>Liu, X. L., Hug, D., Vandersypen, L. M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gate-Defined+Graphene+Double+Quantum+Dot+and+Excited+State+Spectroscopy.">Gate-Defined Graphene Double Quantum Dot and Excited State Spectroscopy.</a> Nano Lett. 10 (5), 1623-1627 (2010).</li><li>Frey, T., Leek, P. J., Beck, M., Blais, A., Ihn, T., Ensslin, K., Wallraff, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dipole+Coupling+of+a+Double+Quantum+Dot+to+a+Microwave+Resonator.">Dipole Coupling of a Double Quantum Dot to a Microwave Resonator.</a> Phys. Rev. Lett. 108, 046807 (2012).</li><li>Pioro-Ladri&#232;re, M., Tokyra, Y., Obata, T., Kubo, T., Tarucha, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micromagnets+for+coherent+control+of+spin-charge+qubit+in+lateral+quantum+dots.">Micromagnets for coherent control of spin-charge qubit in lateral quantum dots.</a> Appl. Phys. Lett. 90 (2), 024105 (2007).</li></ol>

著者らは、開示することは何もありません。

上記の提示処理には数電子政権を達することができる二重量子ドットの作製プロトコルについて説明します。しかし、与えられたパラメータが使用される機器のモデルとキャリブレーションによって異なる場合があります。したがって、このような電子ビームおよびフォトリソグラフィ工程中のエクスポージャーのために投与量などのパラメータは、デバイスの製作の前にキャリブレーショ?...

量子情報科学は、それが量子アルゴリズムが最もよく知られている古典的なアルゴリズム1を用いてより速く急激に特定の問題を解決するために使用することができることが示されて以来、注目を集めている。それは2つのレベルのシステムであるため、量子ビット（キュービット）のための明白な候補者は、量子ドットに閉じ込められた単一電子のスピンです。多数のアーキテクチャは2ナノワイヤー、カーボンナノチューブ3、自己組織化量子ドット4と、半導体5縦方向と横方向の量子ドット06を含む量子ドット半導体の実装の ​​ために提案されている。たGaAs / AlGaAs系で横量子ドットをゲート定義のヘテロ構造があるため、その汎用性の非常に成功しているとその製造プロセスは、この論文の焦点である。 横方向の量子ドット、試料表面に垂直な方向の電子の閉じ込め（Z方向）に一sが適切な基質を選択することによって達成した。のGaAs / AlGaAsの変調ドープされたヘテロ構造には、AlGaAs系とGaAs層との界面に閉じ込められ、二次元電子ガス（2DEG）を提示する。これらのサンプルは変調ドーピング技術と組み合わせることで、低不純物濃度を得るために、分子線エピタキシー法によって成長させ、2DEGの高い電子移動度をもたらす。異なるヘテロ構造の層だけでなく、そのバンド構造の模式図を図1に示す。高電子移動度は、量子ドットの表面全体にわたって電子状態の一貫性を確保するために2DEG必要である。後述の製造プロセスのために使用される基板は、カナダ国立研究評議会から購入し、2.2×10 11 cm -2とし、1.69×10 6 cm 2と / Vsecでの電子移動度の電子密度を示した。 並列方向の電子の閉じ込め試料表面へのLELを、基板の表面上に金属電極を配置することによって達成される。これらの電極は、GaAsの試料の表面に堆積されている場合、ショットキー障壁が7が形成されている。このような電極に印加される負電圧は、十分なエネルギーを持つ電子のみが交差することができ、その下2DEGでローカル障壁につながる。印加電圧がない電子が障壁を横断するのに十分なエネルギーを持っていないことを十分に負である場合に2DEGの枯渇が発生する。したがって、慎重に電極の形状を選択することによって、試料の空乏領域との間の電子の数が少ないをトラップすることができる。ドットならびに試料の残りのドットとの間の2DEGトンネルエネルギーに電子の数の制御は、電極の電圧を微調整することによって達成することができる。ゲート電極の空乏化と電子ガスの概略を図2に示されている。ドットを形成するゲート構造のための設計がされているバーセルらによって使用されたデザインで尖塔のある。8 制御およびドットに電子の数に関する情報を読み出すためには、ドットを介して誘導し、電流を測定することが有用である。読み出しもまた、2DEGを介して電流を必要とする量子点接触（QPC）を使用して行うことができる。 2DEGと電圧源との間の接触はオーミック接触によって保証される。これらには、（ 図3a及び図4bを参照）標準の急速熱アニール工程7を使用して2DEGに試料の表面からのすべての方法を下に拡散される金属製のパッドです。ソースとドレイン間の短絡を回避するために、試料の表面は、2DEGは、特定の領域に空乏化され、電流が特定のチャネル（ 図3b及び図4aを参照）を通過するように強制されるようにエッチングされる。 2DEGは依然として残っている領域は、 &quot;メサ&quot;と呼ばれる。以下のプロトコルの詳細のGaAs / AlGaAsの基板上にゲート定義の横量子ドットの全体の製造プロセス。製造されているデバイスがあっても、シングル、ダブル、またはトリプル量子ドットや量子ドットの配列である場合、それは関係なく、同じままであるため、プロセスはスケーラブルです。操作、測定、およびこの方法を用いて製造された二重量子ドットの結果はさらに、各項に記載されている。

<table border="1">
		<tbody>
 <tr>
 <td>Name of the reagent/material</td>
 <td>Company</td>
 <td>Product number</td>
 <td>CAS number</td>
 </tr>
 <tr>
 <td>Acetone - CH3COCH3</td>
 <td>Anachemia</td>
 <td>AC-0150</td>
 <td>67-64-1</td>
 </tr>
 <tr>
 <td>Isopropyl Alcohol (IPA) - (CH3)2CHOH</td>
 <td>Anachemia</td>
 <td>AC-7830</td>
 <td>67-63-0</td>
 </tr>
 <tr>
 <td>1165 Remover</td>
 <td>MicroChem Corp</td>
 <td>G050200</td>
 <td>872-50-4</td>
 </tr>
 <tr>
 <td>Microposit MF-319 Developer</td>
 <td>Shipley</td>
 <td>38460</td>
 <td>75-59-2</td>
 </tr>
 <tr>
 <td>Sulfuric Acid - H2SO4</td>
 <td>Anachemia</td>
 <td>AC-8750</td>
 <td>766-93-9</td>
 </tr>
 <tr>
 <td>Hydrogen Peroxide (30%) - H2O2</td>
 <td>Fisher Scientific</td>
 <td></td>
 <td>7722-84-1</td>
 </tr>
 <tr>
 <td>LOR 5A Lift-off resist</td>
 <td>MicroChem Corp</td>
 <td>G516608</td>
 <td>120-92-3</td>
 </tr>
 <tr>
 <td>Microposit S1813 Photo Resist</td>
 <td>Shipley</td>
 <td>41280</td>
 <td>108-65-6</td>
 </tr>
 <tr>
 <td>Microposit S1818 Photo Resist</td>
 <td>Shipley</td>
 <td>41340</td>
 <td>108-65-6</td>
 </tr>
 <tr>
 <td>PMMA LMW 4% in anisole</td>
 <td>MicroChem Corp</td>
 <td></td>
 <td>100-66-3, 9011-14-7</td>
 </tr>
 <tr>
 <td>PMMA HMW 2% in anisole</td>
 <td>MicroChem Corp</td>
 <td></td>
 <td>100-66-3, 9011-14-7</td>
 </tr>
 <tr>
 <td >GaAs/AlGaAs wafer</td>
 <td>National Research Council Canada</td>
 <td>See detailed layer structure in Figure 1.</td>
 <td></td>
 </tr>
 <tr>
 <td>Ni (99.0%)</td>
 <td>Anachemia</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Ge (99.999%)</td>
 <td>CERAC inc. </td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Au (99.999%)</td>
 <td>Kamis inc. </td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Ti (99.995%)</td>
 <td>Kurt J Lesker</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Al</td>
 <td>Kamis inc.</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Silver Epoxy</td>
 <td>Epoxy Technology</td>
 <td>H20E</td>
 <td></td>
 </tr>
	 </tbody>
 </table>

nanofabrication of gate-defined gaas/algaas lateral quantum dots

量子コンピュータは、古典的なコンピュータ上で最もよく知られているアルゴリズムで指数関数的により速く特定の問題を解決するために、そのような状態とエンタングルメントの重ね合わせとして、量子効果を活用して、量子ビット（量子）から構成されるコンピュータである。ゲートが定義したGaAs / AlGaAs系で横量子ドットは、量子ビットの実装のために多くの探検道の一つです。適切に製造されたときに、そのようなデバイスは、空間のある領域内の電子の数が少ないをトラップすることができる。これらの電子のスピン状態は、次に量子ビットの論理値0と1を実装するために使用することができる。これらの量子ドットのナノメートルスケールを考えると、特殊な装置 - などの電子顕微鏡や電子ビーム走査として提供クリーンルーム施設その製造に必要な蒸発をラインアップしています。細心の注意は、試料表面の清浄度を維持し、構造の脆弱なゲートの損傷を防ぐために、製造プロセス全体に注意しなければならない。この論文作業装置へのウェハからゲート定義の横量子ドットの詳細な製造プロトコルを提示します。特性評価方法および代表的な結果も簡単に説明されている。本稿では二重の量子ドットに集中していますが、製造プロセスもシングルまたはトリプルドットや量子ドットの配列に対して同じまま。また、プロトコルは、例えば、Si / SiGeのような他の基板上に横方向の量子ドットを製造するために適合させることができる。

上述のプロセスの重要なステップの1つは、メサ（工程1）のエッ​​チングである。オーバーエッチングを回避しながら以下2DEGを除去するのに十分なエッチングすることが重要である。したがって、それは、GaAs / AlGaAs系サンプルでエッチを実行する前に、エッチング液をテストするために、バルクGaAsのダミーサンプルを使用することをお勧めします。のGaAs / AlGaAsのヘテロ構造のエッチング?...

Watch this Scientific Journal Video about Nanofabrication of Gate-defined GaAs/AlGaAs Lateral Quantum Dots at JoVE.com

Nanofabrication of Gate-defined GaAs/AlGaAs Lateral Quantum Dots

本論文では、ガリウム砒素ヘテロ構造上のゲート定義の半導体量子ドットの横の詳細な製造プロトコルを提示します。これらのナノスケールのデバイスは、量子情報処理やコヒーレントコンダクタンス測定などの他のメゾ実験のための量子ビットとして使用するためのいくつかの電子をトラップするために使用される。

ゲート定義のGaAs / AlGaAs系横量子ドットのナノファブリケーション

A quantum computer is a computer composed of quantum bits (qubits) that takes advantage of quantum effects, such as superposition of states and ...

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16.0K ビュー.  Université de Sherbrooke. 本論文では、ガリウム砒素ヘテロ構造上のゲート定義の半導体量子ドットの横の詳細な製造プロトコルを提示します。これらのナノスケールのデバイスは、量子情報処理やコヒーレントコンダクタンス測定などの他のメゾ実験のための量子ビットとして使用するためのいくつかの電子をトラップするために使用される。

ビデオ: Nanofabrication of Gate-defined GaAs/AlGaAs Lateral Quantum Dots

Compact Quantum Dots for Single-molecule Imaging

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study.
Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7.
Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm).

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

1分子蛍光イメージングのためのコンパクトな量子ドット

Single-molecule imaging is an important tool for  understanding the mechanisms of biomolecular function and for visualizing the  spatial and temporal ...

工学

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.

The gradient echo memory is a protocol for storing optical quantum states of light in atomic ensembles. Quantum memory is a key element of a quantum repeater, which can extend the range of quantum key distribution. We outline the operation of the scheme when implemented in a 3-level atomic ensemble.

暖かい原子蒸気に勾配エコー量子メモリ

Gradient  echo memory (GEM) is a protocol for storing optical quantum states of light in  atomic ensembles. The primary motivation for such a technology ...

Analysis of Contact Interfaces for Single GaN Nanowire Devices

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit a strong degradation after annealing due to the occurrence of void formation at the contact/SiO2 interface. This void formation can cause cracking and delamination of the metal film, which can increase the resistance or lead to a complete failure of the NW device. In order to address issues associated with void formation, a technique was developed that removes Ni/Au contact metal films from the substrates to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN NW devices. This procedure determines the degree of adhesion of the contact films to the substrate and NWs and allows for the characterization of the morphology and composition of the contact interface with the substrate and nanowires. This technique is also useful for assessing the amount of residual contamination that remains from the NW suspension and from photolithographic processes on the NW-SiO2 surface prior to metal deposition. The detailed steps of this procedure are presented for the removal of annealed Ni/Au contacts to Mg-doped GaN NWs on a SiO2 substrate.

A technique was developed that removes Ni/Au contact metal films from their substrate to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN nanowire devices.

シングルGaNナノ細線デバイスのための接触界面の解析

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit  a strong degradation after annealing due to the  occurrence of void formation at the ...

Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

This is an instructional paper to guide the construction and diagnostics of external cavity diode lasers (ECDLs), including component selection and optical alignment, as well as the basics of frequency reference spectroscopy and laser linewidth measurements for applications in the field of atomic physics.

原子物理学外部共振器半導体レーザーの構築とキャラクタリゼーション

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and ...

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems3. We focus here on the use of a continuous-wave optical parametric oscillator3,4. This system is based on a non-linear &#967;2 crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. 
Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states5. Generating directly such states is a difficult task and would require strong &#967;3 non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.

We describe the reliable generation of non-Gaussian states of traveling optical fields, including single-photon states and coherent state superpositions, using a conditional preparation method operated on the non-classical light emitted by optical parametric oscillators. Type-I and type-II phase-matched oscillators are considered and common procedures, such as the required frequency filtering or the high-efficiency quantum state characterization by homodyning, are detailed.

連続波光パラメトリック発振器の光の量子状態エンジニアリング

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

液体環境におけるパルスUVレーザー照射によるシリコン表面の濡れ性の選択エリア変更

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Silicon Metal-oxide-semiconductor Quantum Dots for Single-electron Pumping

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by quantum mechanical effects such as tunneling through single dopants, scattering via interface defects, and discrete trap charge states. However, progress in silicon technology has shown that these phenomena can be harnessed and exploited for a new class of quantum-based electronics. Among others, multi-layer-gated silicon metal-oxide-semiconductor (MOS) technology can be used to control single charge or spin confined in electrostatically-defined quantum dots (QD). These QD-based devices are an excellent platform for quantum computing applications and, recently, it has been demonstrated that they can also be used as single-electron pumps, which are accurate sources of quantized current for metrological purposes. Here, we discuss in detail the fabrication protocol for silicon MOS QDs which is relevant to both quantum computing and quantum metrology applications. Moreover, we describe characterization methods to test the integrity of the devices after fabrication. Finally, we give a brief description of the measurement set-up used for charge pumping experiments and show representative results of electric current quantization.

The fabrication process and experimental characterization techniques relevant to single-electron pumps based on silicon metal-oxide-semiconductor quantum dots are discussed.

単電子揚水用のシリコン金属酸化膜半導体量子ドット

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by ...

Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit manipulation, and integrated single-photon detectors. Here, we present the key aspects of preparing and testing a silicon photonic quantum chip with an integrated photon source and two-photon interferometer. The most important aspect of an integrated quantum circuit is minimizing loss so that all of the generated photons are detected with the highest possible fidelity. Here, we describe how to perform low-loss edge coupling by using an ultra-high numerical aperture fiber to closely match the mode of the silicon waveguides. By using an optimized fusion splicing recipe, the UHNA fiber is seamlessly interfaced with a standard single-mode fiber. This low-loss coupling allows the measurement of high-fidelity photon production in an integrated silicon ring resonator and the subsequent two-photon interference of the produced photons in a closely integrated Mach-Zehnder interferometer. This paper describes the essential procedures for the preparation and characterization of high-performance and scalable silicon quantum photonic circuits.

Silicon photonic chips have the potential to realize complex integrated quantum systems. Presented here is a method for preparing and testing a silicon photonic chip for quantum measurements.

シリコンリング共振器光子源における量子干渉の測定

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit ...

Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due to their long coherence time and their capability to manipulate and detect individual quantum bits (qubits). In more recent years, microfabricated surface ion traps have received more attention for large-scale integrated qubit platforms. This paper presents a microfabrication methodology for ion traps using micro-electro-mechanical system (MEMS) technology, including the fabrication method for a 14 &#181;m-thick dielectric layer and metal overhang structures atop the dielectric layer. In addition, an experimental procedure for trapping ytterbium (Yb) ions of isotope 174 (174Yb+) using 369.5 nm, 399 nm, and 935 nm diode lasers is described. These methodologies and procedures involve many scientific and engineering disciplines, and this paper first presents the detailed experimental procedures. The methods discussed in this paper can easily be extended to the trapping of Yb ions of isotope 171 (171Yb+) and to the manipulation of qubits.

This paper presents a microfabrication methodology for surface ion traps, as well as a detailed experimental procedure for trapping ytterbium ions in a room-temperature environment.

微細加工を用いたイオンを捕集する実験方法表面イオン トラップ

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due ...

Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection

The ability to perform simultaneous resonant excitation and fluorescence detection is important for quantum optical measurements of quantum dots (QDs). Resonant excitation without fluorescence detection &#8211; for example, a differential transmission measurement &#8211; can determine some properties of the emitting system, but does not allow applications or measurements based on the emitted photons. For example, the measurement of photon correlations, observation of the Mollow triplet, and realization of single photon sources all require collection of the fluorescence. Incoherent excitation with fluorescence detection &#8211; for example, above band-gap excitation &#8211; can be used to create single photon sources, but the disturbance of the environment due to the excitation reduces the indistinguishability of the photons. Single photon sources based on QDs will have to be resonantly excited to have high photon indistinguishability, and simultaneous collection of the photons will be necessary to make use of them. We demonstrate a method to resonantly excite a single QD embedded in a planar cavity by coupling the excitation beam into this cavity from the cleaved face of the sample while collecting the fluorescence along the sample&#39;s surface normal direction. By carefully matching the excitation beam to the waveguide mode of the cavity, the excitation light can couple into the cavity and interact with the QD. The scattered photons can couple to the Fabry-Perot mode of the cavity and escape in the surface normal direction. This method allows complete freedom in the detection polarization, but the excitation polarization is restricted by the propagation direction of the excitation beam. The fluorescence from the wetting layer provides a guide to align the collection path with respect to the excitation beam. The orthogonality of the excitation and detection modes enables resonant excitation of a single QD with negligible laser scattering background.

Resonant excitation of a single self-assembled quantum dot can be achieved using an excitation mode orthogonal to the fluorescence collection mode. We demonstrate a method using the waveguide and Fabry-Perot modes of a planar microcavity surrounding the quantum dots. The method allows complete freedom in the detection polarization.

直交の励起と検出を用いた平面キャビティ内 InGaAs 量子ドットの共鳴蛍光

The ability to perform simultaneous resonant excitation and fluorescence detection is important for quantum optical measurements of quantum dots (QDs). ...