Quantum Memory Vault

Dec 05, 2024, 02:00 AM Misc Checklist: charge-line filtering >80 dB @5 GHz, flux bias low-noise DC, IR filters & eccosorb. For dots: tune to single-electron regime via

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Checklist: charge-line filtering >80 dB @5 GHz, flux bias low-noise DC, IR filters & eccosorb. For dots: tune to single-electron regime via Coulomb diamonds; extract Ec, lever arm αg. For transmons: measure T1 vs flux, look for TLS; do two-tone spec for |2>. Keep notes of sample ID, cooldown #, wiring map.

Dec 04, 2024, 05:00 AM JavaScript API JS → JJ (conceptual) flow: define schedule in JSON → compile to DAC samples @1 GS/s → IQ mix → drive JJ → transmon. API sketch: await q.setF

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JS → JJ (conceptual) flow: define schedule in JSON → compile to DAC samples @1 GS/s → IQ mix → drive JJ → transmon. API sketch: await q.setFreq(5.12e9); await q.play({shape:"drag", amp:0.32, drag:0.42, phase:0, duration:20e-9}); const {i,q}=await q.measure(); Backend returns demodulated IQ; frontend computes state discrimination. Keep latency <1 µs for active reset/feedback.

Dec 03, 2024, 08:15 AM IQ Pulses IQ baseband: s(t)=I(t)cos(ωt)−Q(t)sin(ωt). I/Q envelopes set rotation angle & phase. DRAG to suppress |1>→|2> leakage: Q(t)=−β·dI/dt with β≈

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IQ baseband: s(t)=I(t)cos(ωt)−Q(t)sin(ωt). I/Q envelopes set rotation angle & phase. DRAG to suppress |1>→|2> leakage: Q(t)=−β·dI/dt with β≈1/(2α). Common shapes: Gaussian (σ≈4–5 ns, 4σ total), DRAG-Gaussian, flat-top with cosine ramps. Calibrate: Rabi for π amplitude, Ramsey for detuning, error-amplification for DRAG β. IQ mixer null LO leakage, correct skew.

Dec 02, 2024, 03:30 AM Transmons Transmon = Josephson Junction + large shunt capacitor. Design: E_J/E_C ~ 50–100 flattens charge dispersion → exponentially insensitive to 1/

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Transmon = Josephson Junction + large shunt capacitor. Design: E_J/E_C ~ 50–100 flattens charge dispersion → exponentially insensitive to 1/f charge noise. Typical ω01/2π = 4–6 GHz, anharmonicity α ≈ -E_C ≈ -200 to -300 MHz. Readout via dispersive coupling to λ/4 resonator (shift χ). T1 limits: dielectric loss, Purcell, quasiparticles. Use Ta/TiN for higher Qi, avoid TLS hotspots.

Dec 01, 2024, 04:00 AM Quantum Dots Quantum dots are size-tunable semiconductor nanocrystals (2–10 nm). Quantum confinement → discrete, atom-like levels with bandgap ~1/r². Key

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Quantum dots are size-tunable semiconductor nanocrystals (2–10 nm). Quantum confinement → discrete, atom-like levels with bandgap ~1/r². Key metrics: charging energy Ec, orbital spacing ΔE, tunnel coupling tc. Applications: spin/valley qubits (Si/SiGe, GaAs), single-photon sources, QD displays. Fabrication: gate-defined 2DEG dots vs colloidal synthesis. Watch valley splitting in Si (>100 µeV target).