SFQ Learning --- Home

Prereqs: none (curriculum entry)
Next: Why superconducting electronics? (express lane)

A guided path from field orientation through device fundamentals, bridge pages, and concept cards into curated tracks. Written so newcomers can follow with patience --- no prior superconductivity course assumed.

Lookup: Glossary · Symbol card (5 symbols) · CMOS vs SFQ (preview anytime)

More pages and more wording are intentional. Prefer clarity over compression --- but use the express lane so you are not forced to read every field guide before symbols.

Who this is for

You are...	Start at
Brand new (first visit)	Express lane below --- then device path
Confused about qubits vs SFQ	Qubits page (canonical contrast) → optional QC platforms
Coming from CMOS	Express lane + preview CMOS vs SFQ
Only need symbols	Symbol card or Notation
Finished fundamentals; cells feel sudden	Bridge
Want click-and-watch demos	Interactive labs
Ready for a guided path	Tracks

Express lane vs full orientation

Express lane (must before device physics) --- about five pages:

1. Why superconducting electronics?
2. History
3. Landscape (airport map; skim field links)
4. Logic families
5. Cryogenics (light)

Then jump to Symbol card → Notation → device fundamentals.

Optional field survey (when titles confuse you --- not required on day one):

• Hub: Field guides
• Especially: Qubits ≠ SFQ · QC platforms
• Skim siblings as needed: sensing, metrology, detectors, cryo-CMOS

1. Fundamentals

Orientation

Must (express lane): why → history → landscape → logic families → cryogenics

Optional: fields/ terminal guides

Device path (core walk)

1. Symbol card --- five-symbol cheatsheet · lab
2. How to read SFQ notation · lab
3. Superconductivity intuition
4. Josephson junction (RCSJ) · lab
5. Flux quantization · lab
6. Superconducting loop / SQUID · lab
7. Overdamped vs underdamped JJ · lab

2. Bridge (close the gap)

Longer, story-first pages between fundamentals and compact SFQ concepts. Do not skip if concepts feel sudden. Each bridge starts with a TL;DR strip.

Start here: bridge/README.md

1. Phase to pulse · lab
2. Pulse to logic state · lab
3. Gate-level pipelining · lab
4. Resistive bias to ERSFQ · lab
5. DC bias current delivery · lab
6. SFQ pulse to voltage levels · lab

3. Concepts

SFQ vocabulary cards. Best after the matching bridge pages.

Logic & interconnects

• RSFQ overview · lab
• JTL interconnects · lab
• Splitter and confluence · lab
• RSFQ DFF and retiming · lab
• ERSFQ logic · lab
• AQFP logic · lab
• CMOS vs SFQ · lab

Clocking, bias, timing, routing

• Concurrent / counter-flow clocking · lab
• Path balancing overhead · lab
• SFQ static timing analysis · lab
• Hybrid JTL-PTL routing · lab
• Serial biasing / current recycling · lab

I/O & memory

• SQUID stack driver · lab
• Four-JL latching driver · lab
• Vortex transitional RAM · lab
• Josephson-CMOS hybrid memory · lab

4. Tracks

• SFQ logic primitives --- primary curated path
• Clocking, biasing & power
• EDA timing & verification
• Cryogenic interfaces & I/O
• Cryogenic memory
• Compute & neuromorphic (public cards TBD)
• Quantum & detector interfaces (public cards TBD)

Interactive labs

In-browser click-and-watch demos (not SPICE). Full list: Labs hub. Each lab also embeds on its matching chapter.