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Anyon-Edge Surface Translation Device
Abundant-Materials Implementation
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TOP-DOWN SCHEMATIC WITH RF TIMING OVERLAY (ASCII REFERENCE)
[Bond Pad Area] [Ohmic 1..4]
╔═══════════════════════════════════════════════════════════════╗
║ ┌───────────────────────────────────────────────────────┐ ║
║ │ ← Chiral Edge Direction (CW under +B field) │ ║
║ │ ┌──────────── Pump / RF Section ────────────────┐ │ ║
║ │ │ G1 (0°) G2 (120°) G3 (240°) │ │ ║
║ │ │ ┌───────┐ ┌───────┐ ┌───────┐ │ │ ║
║ │ │ │ G1 │ │ G2 │ │ G3 │ │ │ ║
║ │ │ └───────┘ └───────┘ └───────┘ │ │ ║
║ │ └───────────────────────────────────────────────┘ │ ║
║ │ [QPC1] [QPC2] │ ║
║ │ █████████ (SLED zone) │ ║
║ │ █ SLED █ │ ║
║ │ █████████ │ ║
║ │ [Hall 1] [Hall 2] │ ║
║ └───────────────────────────────────────────────────────┘ ║
╚═══════════════════════════════════════════════════════════════╝
Timing (qualitative):
G1: sin(ωt + 0°)
G2: sin(ωt + 120°)
G3: sin(ωt + 240°)
Traveling potential along edge: G1 → G2 → G3
Legend:
- Mesa: Racetrack 2D channel (graphene/hBN or Si/SiGe)
- G1/G2/G3: Al pump gates with 120° phase offsets
- QPC1/QPC2: Quantum point contacts for edge density control
- SLED: Pure Fe sled or AlN SAW coupling zone
- Hall sensors: Local ν readout before/after pump region
RF DRIVE SPECIFICATIONS
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Waveform: Sine, 3 phases (0°, 120°, 240°)
Frequency: 10–50 MHz (tuned for coupling/heating)
Amplitude: 0.10–0.20 Vpp at gate
Impedance: 50 Ω lines; cold attenuation as needed
Feedback: Lock filling factor via Hall; adjust DC density/QPCs
CONCEPT AND OBJECTIVE
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Goal: Demonstrate directional surface translation driven by chiral edge transport with IQH → FQH upgrade.
Principle: Tri-phase traveling gate potential pumps edge charge; motion via magnetic or SAW transduction.
Scope: Micro-sled motion on-chip under high B and cryogenic temperatures.
ARCHITECTURE AND LAYOUT (ABUNDANT MATERIALS)
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Platform A (FQH-capable): Graphene/hBN stack
- hBN/graphene/hBN, top/bottom hBN ~20–30 nm
- Edge contacts: Ti/Al or Cr/Al
- Gates: Al on ALD Al2O3
- Piezo: Sputtered AlN for SAW option
- Sled: Pure Fe micro-sled, 200–300 nm thick
Platform B (IQH demo): Si/SiGe 2DEG
- Contacts: Al-based ohmics
- Gates: Al on Al2O3
- Same sled/piezo options as above
Common geometry:
- Racetrack perimeter ~2 mm; track width 3–5 µm
- Three pump gates, 100 µm long, 2 µm gaps
- Two QPCs, 300–400 nm gap
- Spacer: ALD Al2O3 50–100 nm over active edge
- Hall sensors: Graphene or Si Hall crosses
OPERATING CONDITIONS AND TARGETS
---------------------------------
Graphene/hBN:
- B-field: 6–9 T (IQH), 10–14 T (FQH ν=1/3)
- Temp: 1.5–4.2 K (IQH), 50–300 mK (FQH)
- Mobility: > 50,000 cm²/V·s post-fab
Si/SiGe:
- B-field: 6–9 T (IQH)
- Temp: 4.2 K
- Mobility: > 100,000 cm²/V·s
Drive/motion (both):
- Edge current: 0.5–10 µA modulated
- Gate drive: 0.10–0.20 Vpp, 10–50 MHz, 0°/120°/240°
- Force: ~nN scale (magnetic sled) or equivalent SAW drag
- Velocity: 1–100 µm/s
BILL OF MATERIALS (ABUNDANT SOURCES)
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- Graphene: CVD-grown or exfoliated monolayer
- hBN: Exfoliated or CVD-grown
- Si/SiGe wafers: Commercial CMOS suppliers
- Contacts: Ti, Al, Cr (all abundant)
- Gates: Al
- Dielectric: ALD Al2O3 or SiO2
- Piezo: AlN sputter target
- Sled: Pure Fe or FeCo alloy
- Spacer: ALD Al2O3
- Wiring: Al or Cu (with barrier layer)
BUILD PLAN
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Phase 1 (IQH, abundant platform):
- Fabricate on Si/SiGe or graphene/hBN
- Pattern mesa, deposit Al gates, form Al or Ti/Al contacts
- Integrate Fe sled or AlN SAW
- Test at 4.2 K, 6–9 T; verify IQH plateaus and motion
Phase 2 (FQH, graphene/hBN):
- Use high-mobility encapsulated graphene
- Dilution fridge to 50–300 mK; B up to 14 T
- Tune to ν=1/3; repeat motion demo
RISKS AND MITIGATION
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RF heating: Lower Vpp, cold attenuators, pulsed drive
Sled stiction: Use SAW coupling, smoother spacer, smaller contact area
FQH sensitivity: Higher mobility, better shielding, edge smoothness
Backscattering: Optimize QPC geometry and gate alignment
MILESTONES
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M1: IQH plateaus, QPC control
M2: Unidirectional pumping with phase control
M3: Repeatable sled displacement vs. frequency/amplitude
M4: FQH ν = 1/3 operation with stable motion
FORCE CALCULATION (MAGNETIC SLED OPTION)
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Given:
- Edge current I = 1 µA (modulated)
- Distance from edge to sled magnet center r ≈ 100 nm
- Magnetic moment of sled m ≈ M_s × V
M_s (Fe saturation magnetization) ≈ 1.7×10^6 A/m
V = 12 µm × 12 µm × 0.3 µm = 4.32×10^-17 m³
⇒ m ≈ 7.34×10^-11 A·m²
Magnetic field from edge current (Biot–Savart):
B ≈ μ₀ I / (2π r)
B ≈ (4π×10^-7 × 1×10^-6) / (2π × 1×10^-7) ≈ 2×10^-6 T
Field gradient:
∇B ≈ B / r ≈ (2×10^-6) / (1×10^-7) = 20 T/m
Force on sled:
F ≈ m × ∇B ≈ (7.34×10^-11) × 20 ≈ 1.47×10^-9 N (~1.5 nN)
Implication:
- At cryo with ultra-low friction, this is enough to move a nanogram-scale sled at µm/s speeds.
- Scaling I to 10 µA boosts force ~10×.
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