\Part[ \eng{Quantum Computing} \ger{Quantencomputing} ]{qc} \Section[ \eng{Qubits} \ger{Qubits} ]{qubit} \begin{formula}{bloch_sphere} \desc{Bloch sphere}{}{} \desc[german]{Bloch-Sphäre}{}{} \eq{ \ket{\psi} &= \alpha \ket{0} + \beta \ket{1} \\ &= \cos \frac{\theta}{2} \e^{i\phi_\alpha} \ket{0} + \sin{\frac{\theta}{2} \e^{i\phi_\beta}} \ket{1} \\ &= \e^{i\phi_\alpha} \cos\frac{\theta}{2} \ket{0} + \sin\frac{\theta}{2} \e^{i\phi} \ket{1} } \end{formula} \Section[ \eng{Gates} \ger{Gates} ]{gates} \begin{formula}{gates} \desc{}{}{} \desc[german]{}{}{} \begin{alignat}{2} & \text{\gt{bitflip}:} & \hat{X} &= \sigma_x = \sigmaxmatrix \\ & \text{\gt{bitphaseflip}:} & \hat{Y} &= \sigma_y = \sigmaymatrix \\ & \text{\gt{phaseflip}:} & \hat{Z} &= \sigma_z = \sigmazmatrix \\ & \text{\gt{hadamard}:} & \hat{H} &= \frac{1}{\sqrt{2}}(\hat{X}-\hat{Z}) = \begin{pmatrix} 1 & 1 \\ 1 & -1 \end{pmatrix} \end{alignat} \end{formula} % \begin{itemize} % \item \gt{bitflip}: $\hat{X} = \sigma_x = \sigmaxmatrix$ % \item \gt{bitphaseflip}: $\hat{Y} = \sigma_y = \sigmaymatrix$ % \item \gt{phaseflip}: $\hat{Z} = \sigma_z = \sigmazmatrix$ \item \gt{hadamard}: $\hat{H} = \frac{1}{\sqrt{2}}(\hat{X}-\hat{Z}) = \begin{pmatrix} 1 & 1 \\ 1 & -1 \end{pmatrix}$ % \end{itemize} \Section[ \eng{Superconducting qubits} \ger{Supraleitende qubits} ]{scq} \Subsection[ \eng{Building blocks} \ger{Bauelemente} ]{elements} \Subsubsection[ \eng{Josephson Junction} \ger{Josephson-Kontakt} ]{josephson_junction} \begin{ttext}[desc] \eng{When two superconductors are separated by a thin isolator, Cooper pairs can tunnel through the insulator. The Josephson junction is a non-linear inductor.} \ger{Wenn zwei Supraleiter durch einen dünnen Isolator getrennt sind, können Cooper-Paare durch den Isolator tunneln. Der Josephson-Kontakt ist ein nicht-linearer Induktor.} \end{ttext} \begin{formula}{hamiltonian} \desc{Josephson-Hamiltonian}{}{} \desc[german]{Josephson-Hamiltonian}{}{} \eq{ \hat{H}_\text{J} &= - \frac{E_\text{J}}{2} \sum_n [\ket{n}\bra{n+1} + \ket{n+1}\bra{n}] } \end{formula} \begin{formula}{1st_josephson_relation} \desc{1. Josephson relation}{Dissipationless supercurrent accros junction at zero applied voltage}{$I_\text{C}=\frac{2e}{\hbar}E_\text{J}$ critical current, $\delta$ phase difference accross junction} \desc[german]{1. Josephson Gleichung}{Dissipationsloser Suprastrom durch die Kreuzung ohne angelegte Spannung}{$I_\text{C}=\frac{2e}{\hbar}E_\text{J}$ kritischer Strom, $\delta$ Phasendifferenz zwischen den Supraleitern} \eq{\hat{I}\ket{\delta} = I_\text{C}\sin\delta \ket{\delta}} \end{formula} \begin{formula}{2nd_josephson_relation} \desc{2. Josephson relation}{superconducting phase change is proportional to applied voltage}{$\varphi_0=\frac{\hbar}{2e}$ reduced flux quantum} \desc[german]{2. Josephson Gleichung}{Supraleitende Phasendifferenz is proportional zur angelegten Spannung}{$\varphi_0=\frac{\hbar}{2e}$ reduziertes Flussquantum} \eq{\odv{\hat{\delta}}{t}=\frac{1}{i\hbar}[\hat{H},\hat{\delta}] = -\frac{2eU}{i\hbar}[\hat{n},\hat{\delta}] = \frac{1}{\varphi_0} U} \end{formula} \Subsubsection[ \eng{SQUID} \ger{SQUID} ]{squid} \ctikzsubcircuitdef{squidloop}{n, s, nw, ne, se, sw}{ % start at top coordinate(#1-n) (#1-n) to ++(-1, 0) coordinate(#1-nw) to[josephsoncap=$\phi_1$] ++(0,-2) coordinate(#1-sw) to ++(1,0) coordinate(#1-s) to ++(1,0) coordinate(#1-se) to[josephsoncap=$\phi_2$] ++(0,2) coordinate(#1-ne) to ++(-1,0) (#1-s) % leave at bottom } \begin{formula}{circuit} \desc{SQUID}{Superconducting quantum interference device, consists of parallel \hyperref{sec:qc:scq:josephson_junction}{josephson junctions}, can be used to measure extremely weak magnetic fields}{} \desc[german]{SQUID}{Superconducting quantum interference device, besteht aus parralelen \hyperref{sec:qc:scq:josephson_junction}{Josephson Junctions} und kann zur Messung extrem schwacher Magnetfelder genutzt werden}{} \centering \begin{tikzpicture} \draw (0, 0) \squidloop{loop}{}; \end{tikzpicture} \end{formula} \begin{formula}{hamiltonian} \desc{Hamiltonian}{}{$\hat{\phi}$ phase difference across the junction} \desc[german]{Hamiltonian}{}{$\hat{\phi}$ Phasendifferenz an einer Junction} \eq{\hat{H} &= -E_{\text{J}1} \cos\hat{\phi}_{1} - E_{\text{J}2} \cos\hat{\phi}_{2}} \end{formula} \Subsection[ \eng{Josephson Qubit??} \ger{TODO} ]{josephson_qubit} \begin{tikzpicture} \draw (0,0) to[capacitor] (0,2); \draw (0,0) to (2,0); \draw (0,2) to (2,2); \draw (2,0) to[josephson] (2,2); \draw[->] (3,1) -- (4,1); \draw (5,0) to[josephsoncap=$C_\text{J}$] (5,2); \end{tikzpicture} \TODO{Include schaltplan} \begin{tikzpicture} \draw (0,0) to[sV=$V_\text{g}$] (0,2); \draw (0,2) to[capacitor=$C_\text{g}$] (2,2); \draw (2,2) to (4,2); \draw (2,0) to[josephsoncap=$C_\text{J}$] (2,2); \draw (4,0) to[capacitor=$C_C$] (4,2); \draw (0,0) to (2,0); \draw (2,0) to (4,0); \end{tikzpicture} \begin{formula}{charging_energy} \desc{Charging energy / electrostatic energy}{}{} \desc[german]{Ladeenergie?}{}{} \eq{E_\text{C} = \frac{(2e)^2}{C}} \end{formula} \begin{formula}{josephson_energy} \desc{Josephson energy}{}{} \desc[german]{Josephson-Energie?}{}{} \eq{E_\text{J} = \frac{I_0 \phi_0}{2\pi}} \end{formula} \TODO{Was ist I0} \begin{formula}{inductive_energy} \desc{Inductive energy}{}{} \desc[german]{Induktive Energie}{}{} \eq{E_\text{L} = \frac{\varphi_0^2}{L}} \end{formula} \begin{formula}{gate_charge} \desc{Gate charge}{or offset charge}{} \desc[german]{Gate Ladung}{auch Offset charge}{} \eq{n_\text{g}=\frac{C_g V_\text{g}}{2e}} \end{formula} \begin{formula}{anharmonicity} \desc{Anharmonicity}{}{} \desc[german]{Anharmonizität}{}{} \eq{\alpha \coloneq \omega_{1\leftrightarrow 2} - \omega_{0\leftrightarrow 1}} \end{formula} \begin{minipage}{0.8\textwidth} \begingroup \setlength{\tabcolsep}{0.9em} % horizontal \renewcommand{\arraystretch}{2} % vertical \begin{tabular}{ p{0.5cm} |p{0.8cm}||p{2.2cm}|p{1.9cm}|p{1.9cm}|p{1.8cm}|} \multicolumn{1}{c}{}& \multicolumn{1}{c}{} &\multicolumn{4}{c}{$E_L/(E_J-E_L)$} \\ \cline{3-6} \multicolumn{1}{c}{} & & $0$ & $\ll$ 1 & $\sim 1$ & $\gg 1$\\ \hhline{~|=====|} \multirow{4}{*}{$\frac{E_J}{E_C}$} & $\ll 1$ & cooper-pair box & & & \\ \cline{2-6} & $\sim 1$ & quantronium & fluxonium & &\\ \cline{2-6} & $\gg 1$ &transmon & & & flux qubit\\ \cline{2-6} & $\ggg 1$ & & & phase qubit & \\ \cline{2-6} \end{tabular} \endgroup \end{minipage} \begin{minipage}{0.2\textwidth} \begin{tikzpicture}[scale=2] \draw[-latex,line width=2pt] (0,1)--++(0,1) node[midway,above,sloped] () {charge noise}; \draw[-latex,line width=2pt] (0,1)--++(0,1) node[midway,below,sloped] () {sensitivity}; \draw[-latex,line width=2pt] (0,0)--++(1,1) node[midway,above,sloped] () {flux noise}; \draw[-latex,line width=2pt] (0,0)--++(1,1) node[midway,below,sloped] () {sensitivity}; \draw[-latex,line width=2pt] (0,0)--++(1,-1) node[midway,above,sloped] () {critical current}; \draw[-latex,line width=2pt] (0,0)--++(1,-1) node[midway,below,sloped] () {noise sensitivity}; \end{tikzpicture} \end{minipage} \Subsection[ \eng{Cooper Pair Box (CPB) qubit} \ger{Cooper Paar Box (QPB) Qubit} ]{cpb} \begin{ttext} \eng{ = voltage bias junction\\= charge qubit? } \ger{} \end{ttext} \begin{formula}{circuit} \desc{Cooper Pair Box / Charge qubit}{ \begin{itemize} \gooditem large anharmonicity \baditem sensitive to charge noise \end{itemize} }{} \desc[german]{Cooper Pair Box / Charge Qubit}{ \begin{itemize} \gooditem Große Anharmonizität \baditem Sensibel für charge noise \end{itemize} }{} \centering \begin{tikzpicture} \draw (0,0) to[sV=$V_\text{g}$] (0,2); % \draw (0,0) to (2,0); \draw (0,2) to[capacitor=$C_\text{g}$] (2,2); \draw (2,0) to[josephsoncap=$C_\text{J}$] (2,2); \draw (0,0) to (2,0); \end{tikzpicture} \end{formula} \begin{formula}{hamiltonian} \desc{Hamiltonian}{}{} \desc[german]{Hamiltonian}{}{} \eq{\hat{H} &= 4 E_C(\hat{n} - n_\text{g})^2 - E_\text{J} \cos\hat{\phi} \\ &=\sum_n \left[4 E_C (n-n_\text{g})^2 \ket{n}\bra{n} - \frac{E_\text{J}}{2}\ket{n}\bra{n+1}+\ket{n+1}\bra{n}\right] } \end{formula} \Subsection[ \eng{Transmon qubit} \ger{Transmon Qubit} ]{transmon} \begin{formula}{circuit} \desc{Transmon qubit}{ Josephson junction with a shunt \textbf{capacitance}. \begin{itemize} \gooditem charge noise insensitive \baditem small anharmonicity \end{itemize} }{} \desc[german]{Transmon Qubit}{ Josephson-Kontakt mit einem parallelen \textbf{kapzitiven Element}. \begin{itemize} \gooditem Charge noise resilient \baditem Geringe Anharmonizität $\alpha$ \end{itemize} }{} \centering \begin{tikzpicture} % \draw (0,0) to[sV=$V_\text{g}$] ++(0,3) % to[capacitor=$C_\text{g}$] ++(2,0) \draw (0,0) to ++(2,0) to ++(0,-0.5) to[josephsoncap=$C_\text{J}$] ++(-0,-2) to ++(0,-0.5) to ++(-2,0) to[capacitor=$C_C$] ++(0,3); \end{tikzpicture} \end{formula} \begin{formula}{hamiltonian} \desc{Hamiltonian}{}{} \desc[german]{Hamiltonian}{}{} \eq{\hat{H} &= 4 E_C\hat{n}^2 - E_\text{J} \cos\hat{\phi}} \end{formula} \Subsubsection[ \eng{Tunable Transmon qubit} \ger{Tunable Transmon Qubit} ]{tunable} \begin{formula}{circuit} \desc{Frequency tunable transmon}{By using a \fqSecRef{qc:scq:elements:squid} instead of a \fqSecRef{qc:scq:elements:josephson_junction}, the qubit is frequency tunable through an external field}{} \desc[german]{}{Durch Nutzung eines \fqSecRef{qc:scq:elements:squid} anstatt eines \fqSecRef{qc:scq:elements:josephson_junction}s, ist die Frequenz des Qubits durch ein externes Magnetfeld einstellbar}{} \centering \begin{tikzpicture} % \draw (0,0) to[sV=$V_\text{g}$] ++(0,3) % to[capacitor=$C_\text{g}$] ++(2,0) \draw (0,0) to ++(-2,0) to ++(3,0) to ++(0,-0.5) \squidloop{loop}{SQUID} to ++(0,-0.5) to ++(-3,0) to[capacitor=$C_C$] ++(0,3); \end{tikzpicture} \end{formula} \begin{formula}{energy} \desc{Josephson energy}{}{$d=(E_\text{J1}-E_\text{J2})/(E_\text{J1}+E_\text{J2})$ asymmetry} \desc[german]{Josephson Energie}{}{$d=(E_\text{J1}-E_\text{J2})/(E_\text{J1}+E_\text{J2})$ Asymmetrie} \eq{E_\text{J,eff}(\Phi_\text{ext}) = (E_\text{J1}+E_\text{J2}) \sqrt{\cos^2\left(\pi\frac{\Phi_\text{ext}}{\Phi_0}\right) + d^2 \sin \left(\pi\frac{\Phi_\text{ext}}{\Phi_0}\right)}} \end{formula} \begin{formula}{hamiltonian} \desc{Hamiltonian}{}{} \desc[german]{Hamiltonian}{}{} \eq{\hat{H} = 4E_C \hat{n}^2 - \frac{1}{2} E_\text{J,eff}(\Phi_\text{ext}) \sum_{n}\left[\ket{n}\bra{n+1} + \ket{n+1}\bra{n}\right]} \end{formula} \begin{figure}[h] \centering \includegraphics[width=0.8\textwidth]{img/qubit_transmon.pdf} \caption{Transmon and so TODO} \label{fig:img-qubit_transmon-pdf} \end{figure} \Subsection[ \eng{Phase qubit} \ger{Phase Qubit} ]{phase} \begin{formula}{circuit} \desc{Phase qubit}{}{} \desc[german]{Phase Qubit}{}{} \centering \begin{tikzpicture} % \draw (0,0) to[sV=$V_\text{g}$] ++(0,3) % to ++(2,0) coordinate(top1) % to ++(2,0) coordinate(top2) % to ++(2,0) coordinate(top3); % \draw (0,0) % to ++(2,0) coordinate(bot1) % to ++(2,0) coordinate(bot2) % to ++(2,0) coordinate(bot3); \draw[color=gray] (0,0) to[capacitor=$C_C$] (0,-2); % \draw (top1) to ++(0,-0.5) to[josephsoncap=$C_\text{J}$] ++(-0,-2) to (bot2); \draw(0,0) to ++(2,0) to[josephsoncap=$C_\text{J}$] ++(0,-2) to ++(-2,0); \draw (2,0) to ++(2,0) to[cute inductor=$E_L$] ++(0,-2) to ++(-2,0); \node at (3,-1.5) {$\Phi_\text{ext}$}; \end{tikzpicture} \\\TODO{Ist beim Fluxonium noch die Voltage source dran?} \end{formula} \begin{formula}{hamiltonian} \desc{Hamiltonian}{}{$\delta = \frac{\phi}{\phi_0}$} \desc[german]{Hamiltonian}{}{} \eq{\hat{H} = E_C \hat{n}^2 - E_J \cos \hat{\delta} + E_L(\hat{\delta} - \delta_s)^2} \end{formula} \Eng[TESTT]{This is only a test} \Ger[TESTT]{} \GT{TESTT} \Subsection[ \eng{Flux qubit} \ger{Flux Qubit} ]{flux} \TODO{TODO} \begin{formula}{circuit} \desc{Flux qubit / Persistent current qubit}{}{} \desc[german]{Flux Qubit / Persistent current qubit}{}{} \centering \begin{tikzpicture} \draw (0,0) to[josephsoncap=$\alpha E_\text{J}$, scale=0.8, transform shape] (0,-3); \draw (0,0) to ++(3,0) to[josephsoncap=$E_\text{J}$] ++(0,-1.5) to[josephsoncap=$E_\text{J}$] ++(0,-1.5) to ++(-3,0); \node at (1.5,-1.5) {$\Phi_\text{ext}$}; \end{tikzpicture} % \begin{tikzpicture} % \draw (0,0) to[sV=$V_\text{g}$] ++(0,3) % to ++(2,0) coordinate(top1) % to ++(2,0) coordinate(top2) % to ++(2,0) coordinate(top3); % \draw (0,0) % to ++(2,0) coordinate(bot1) % to ++(2,0) coordinate(bot2) % to ++(2,0) coordinate(bot3); % \draw[color=gray] (top1) to[capacitor=$C_C$] (bot1); % % \draw (top1) to ++(0,-0.5) to[josephsoncap=$C_\text{J}$] ++(-0,-2) to (bot2); % \draw[scale=0.8, transform shape] (top2) to[josephsoncap=$\alpha E_\text{J}$] (bot2); % \draw (top3) % to[josephsoncap=$E_\text{J}$] ++(0,-1.5) % to[josephsoncap=$E_\text{J}$] (bot3); % \node at (5,0.5) {$\Phi_\text{ext}$}; % \end{tikzpicture} \end{formula} \Subsection[ \eng{Fluxonium qubit} \ger{Fluxonium Qubit} ]{fluxonium} \begin{formula}{circuit} \desc{Fluxonium qubit}{ Josephson junction with a shunt \textbf{inductance}. Instead of having to tunnel, cooper pairs can move to the island via the inductance. The inductance consists of many parallel Josephson Junctions to avoid parasitic capacitances. }{} \desc[german]{Fluxonium Qubit}{ Josephson-Kontakt mit einem parallelen \textbf{induktiven Element}. Anstatt zu tunneln, können die Cooper-Paare über das induktive Element auf die Insel gelangen. Das induktive Element besteht aus sehr vielen parallelen Josephson-Kontakten um parisitische Kapazitäten zu vermeiden. }{} \centering \begin{tikzpicture} % \draw (0,0) to[sV=$V_\text{g}$] ++(0,3) % to ++(2,0) coordinate(top1); \draw[color=gray] (0,0) to ++(-2,0) to[capacitor=$C_C$] ++(0,-3) to ++(2,0); \draw (0,0) to[josephsoncap=$C_\text{J}$] ++(-0,-3); \draw (0,0) to ++(2,0) to[cute inductor=$E_L$] ++(0,-3) to ++(-2,0); \node at (1,-0.5) {$\Phi_\text{ext}$}; \end{tikzpicture} \\\TODO{Ist beim Fluxonium noch die Voltage source dran?} \end{formula} \def\temp{$E_\text{C} = \frac{(2e)^2}{2C}, E_\text{L} = \frac{\varphi_0^2}{2L}, \delta_\text{s} = \frac{\varphi_\text{s}}{\varphi_0}$} \begin{formula}{hamiltonian} \desc{Hamiltonian}{}{\temp} \desc[german]{Hamiltonian}{}{\temp} \eq{\hat{H} = 4E_\text{C} \hat{n}^2 - E_\text{J} \cos \hat{\delta} + E_\text{L}(\hat{\delta} - \delta_\text{s})^2} \end{formula} \begin{figure}[h] \centering \includegraphics[width=\textwidth]{img/qubit_flux_onium.pdf} \caption{img/} \label{fig:img-} \end{figure} \Section[ \eng{Two-level system} \ger{Zwei-Niveau System} ]{stuff} \begin{formula}{resonance_frequency} \desc{Resonance frequency}{}{} \desc[german]{Ressonanzfrequenz}{}{} \eq{\omega_{21} = \frac{E_2 - E_1}{\hbar}} \end{formula} \TODO{sollte das nicht 10 sein?} \begin{formula}{rabi_oscillation} \desc{Rabi oscillations}{}{$\omega_{21}$ resonance frequency of the energy transition, $\Omega$ Rabi frequency} \desc[german]{Rabi-Oszillationen}{}{$\omega_{21}$ Resonanzfrequenz des Energieübergangs, $\Omega$ Rabi-Frequenz} \eq{\Omega_ \text{\TODO{TODO}}} \end{formula} \Subsection[ \eng{Ramsey interferometry} \ger{Ramsey Interferometrie} ]{ramsey} \begin{ttext} \eng{$\ket{0} \xrightarrow{\frac{\pi}{2}\,\text{pulse}}$ precession in $xy$ plane for time $\tau$ $\xrightarrow{\frac{\pi}{2}\,\text{pulse}}$ measurement} \ger{q} \end{ttext} \Section[ \eng{Noise and decoherence} \ger{Noise und Dekohärenz} ]{noise} \begin{formula}{long} \desc{Longitudinal relaxation rate}{$\Gamma_{1\downarrow}$: $\ket{1}\rightarrow \ket{0}$ \\ $\Gamma_{1\uparrow}$: $\ket{0}\rightarrow \ket{1}$}{} \desc[german]{Longitudinale Relaxationsrate}{$\Gamma_{1\downarrow}$: $\ket{1}\rightarrow \ket{0}$ \\ $\Gamma_{1\uparrow}$: $\ket{0}\rightarrow \ket{1}$}{} \eq{\Gamma_1 = \frac{1}{T_1} = \Gamma_{1\uparrow} + \Gamma_{1\downarrow}} \end{formula} \begin{ttext}[long] \eng{$\Gamma_{1\uparrow}$ is supressed at low temperatures because of detailed balance} \ger{$\Gamma_{1\uparrow}$ ist bei niedrigen Temperaturen unterdrückt wegen detailed balance} \end{ttext} \begin{formula}{dephasing} \desc{Pure dephasing rate}{}{} \desc[german]{Reine Phasenverschiebung}{}{} \eq{\Gamma_\phi} \end{formula} \begin{formula}{trans} \desc{Transversal relaxation rate}{}{} \desc[german]{Transversale Relaxationsrate}{}{} \eq{\Gamma_2 = \frac{1}{T_2} = \frac{\Gamma_1}{2} + \Gamma_\phi} \end{formula} \begin{formula}{bloch_redfield} \desc{Bloch-Redfield density matrix}{2-level System weakly coupled to noise sources with short correlation time}{} \desc[german]{Bloch-Redfield Dichtematrix}{2-Niveau System schwach an Noise Quellen mit kurzer Korrelationszeit gekoppelt}{} \eq{\rho_\text{BR} = \begin{pmatrix} 1+(\abs{\alpha}^2-1)\e^{-\Gamma_1 t} & \alpha \beta^* \e^{-\Gamma_2 t} \\ \alpha^*\beta \e^{-\Gamma_2 t} & \abs{\beta}^2 \e^{-\Gamma_1 t} \end{pmatrix} } \end{formula}