# Quantum Computing — A Different Kind of Computer Canonical URL: https://shipslides.com/d/catalog-future-quantum-computing Raw viewer URL: https://content.shipslides.com/d/catalog-future-quantum-computing/raw Category: Future Slides: 13 Updated: 2026-05-17T20:55:58.095Z Tags: catalog, future, quantum, computing ## Summary Classical bits are switches: 0 or 1, definite at every instant. A qubit is a quantum object whose state is a continuous combination — a superposition — of 0 and 1, collapsing only when measured. Key sections include: QUANTUM COMPUTING A different kind of computer.; A bit holds one answer. A qubit holds both.; Superposition. Entanglement.; The Bloch sphere; Feynman, 1982; Shor's algorithm breaks RSA; Grover: √N search; Four serious hardware bets; Qubits are delicate; Logical qubits, demonstrated. ## Slide Outline 1. QUANTUM COMPUTING A different kind of computer. 2. A bit holds one answer. A qubit holds both. 3. Superposition. Entanglement. 4. The Bloch sphere 5. Feynman, 1982 6. Shor's algorithm breaks RSA 7. Grover: √N search 8. Four serious hardware bets 9. Qubits are delicate 10. Logical qubits, demonstrated 11. Quantum advantage is hard to define 12. Years away. Worth building anyway. 13. Keep learning. ## Slide Transcript ### Slide 1: QUANTUM COMPUTING A different kind of computer. - A primer on the future of compute - 13 SLIDES · EST 12 MIN - FIELD · PHYSICS / CS - ERA · 1982 — NOW ### Slide 2: A bit holds one answer. A qubit holds both. - 02 — Foundations - Classical bits are switches: 0 or 1, definite at every instant. A qubit is a quantum object whose state is a continuous combination — a superposition — of 0 and 1, collapsing only when measured. - CLASSICAL BIT - 0 | 1 - Definite. Copyable. One state at a time. - QUBIT - α|0⟩ + β|1⟩ - Probabilistic until measured. |α|² + |β|² = 1. ### Slide 3: Superposition. Entanglement. - 03 — Two quantum resources - Quantum advantage rides on two phenomena no classical machine can fake. Together they let an n-qubit register encode 2ⁿ amplitudes in parallel — and steer them with interference. - RESOURCE 01 - Superposition - A single qubit lives on a continuum between |0⟩ and |1⟩. n qubits explore 2ⁿ possibilities at once — though we only get one classical answer when we look. - RESOURCE 02 - Entanglement - Qubits can share a joint state that cannot be written as a product of parts. Measuring one instantly constrains the other — Einstein's "spooky action." ### Slide 4: The Bloch sphere - 04 — Geometry of a qubit - Every pure single-qubit state is a point on the surface of a unit sphere. The north pole is |0⟩, the south is |1⟩, and the equator is equal superposition. Operations are rotations; measurement collapses the vector to a pole. ### Slide 5: Feynman, 1982 - 05 — The seed idea - "Nature isn't classical, dammit." Simulating molecules and materials on classical hardware demands resources that grow exponentially with system size. Feynman's proposal: build a computer out of quantum stuff to model quantum stuff. - It would take another decade for the field to take shape — but every quantum algorithm that followed traces back to this lecture. - "Nature isn't classical, dammit, and if you want to make a simulation of nature, you'd better make it quantum mechanical." - — RICHARD FEYNMAN · MIT KEYNOTE · 1981/82 ### Slide 6: Shor's algorithm breaks RSA - 06 — The factoring algorithm - In 1994 Peter Shor showed a quantum computer can factor an n-bit integer in polynomial time — exponentially faster than the best known classical method. RSA, which secures most of the internet, derives all its strength from factoring being hard. - CLASSICAL · BEST - ~exp(n1/3) - General number field sieve. Sub-exponential, still ruinous at large n. - SHOR · QUANTUM - ~n³ - Polynomial. A 2048-bit RSA key falls in hours, given enough fault-tolerant qubits. - REQUIREMENT - ~10⁷ qb - Recent estimates for breaking RSA-2048 with realistic error rates. We are not there yet. ### Slide 7: Grover: √N search - 07 — Search - Two years after Shor, Lov Grover showed how to find a marked item in an unsorted database of N entries using only ≈√N queries. Not exponential — but a quadratic speedup that applies to a vast class of search-shaped problems. - 1996 · BELL LABS - Brute-force AES-256 drops from 2²⁵⁶ to 2¹²⁸ — still infeasible. The win is in optimization, satisfiability, ML kernels. ### Slide 8: Four serious hardware bets - 08 — Building the thing - No consensus on the right physical substrate. Every approach trades coherence time, gate fidelity, connectivity and clock speed differently. The race is wide open. - Superconducting circuits - Google · IBM · Rigetti · Quantum Circuits - Fast gates, scalable lithography. Needs millikelvin dilution refrigerators. - Trapped ions - IonQ · Quantinuum · AQT - Long coherence, high fidelity, all-to-all connectivity. Slower clock. - Photonic - PsiQuantum · Xanadu - Room-temperature, networking-friendly. Probabilistic gates, high losses. - Neutral atoms - QuEra · Atom Computing · Pasqal - Reconfigurable arrays, recently scaled past 1000 atoms. Newest contender. ### Slide 9: Qubits are delicate - 09 — The wall - Decoherence, gate errors, readout errors — physical qubits today have error rates around 10⁻³ per operation. Useful algorithms need ~10⁻¹⁵. The fix is quantum error correction: encode one logical qubit across many noisy physical ones. - ~1,000 phys - → per logical qubit - 10−3 - today's gate error - 10−15 - target for shor-scale tasks ### Slide 10: Logical qubits, demonstrated - 10 — 2024–25 milestones - For the first time, logical qubits are outperforming their underlying physical components. Crossing this threshold means scaling adds reliability — error correction is no longer theoretical. - GOOGLE · 2024 - Below threshold - Surface-code distance-7 logical qubit shows error suppression that improves as code distance grows. - QUANTINUUM · 2024 - 12 logical qubits - Trapped-ion processor entangles 12 high-fidelity logical qubits with magic-state distillation. - QUERA · 2024 - 48 logical qubits - Neutral-atom array runs algorithms on dozens of logical qubits — largest demo to date. ### Slide 11: Quantum advantage is hard to define - 11 — What counts as a win? - There are demonstrations where quantum hardware solves a contrived task faster than any known classical method — sampling random circuits, boson sampling, certain spin-glass problems. Whether they are useful is a separate question. Classical algorithms keep catching up too. - 2019 · GOOGLE SYCAMORE - Random circuit sampling - 53 qubits. First claimed "supremacy." Subsequent classical methods narrowed the gap. - 2020 · USTC JIUZHANG - Photonic boson sampling - Independent demonstration on a fundamentally different platform. - 2024 · GOOGLE - RCS at higher fidelity - Larger, harder-to-spoof random circuit sampling on the Willow chip. - OPEN - Useful advantage - No public, scientifically-significant problem yet solved faster on a quantum machine end-to-end. ### Slide 12: Years away. Worth building anyway. - 12 — The honest read - Quantum computing is over-hyped on the short horizon and arguably under-appreciated on the long one. The realistic timeline for broadly useful machines is measured in years to a decade-plus, not quarters. The prize, if it lands, is genuinely transformational. - NEAR TERM · BE SKEPTICAL - No commercial application yet pays for itself - NISQ-era machines too noisy for deep circuits - Crypto threat is real but years off — not tomorrow - Many "quantum" use-cases are classical in disguise - LONG TERM · TAKE IT SERIOUSLY - Chemistry & materials simulation: catalysts, batteries, drugs - Cryptanalysis — and post-quantum crypto is already deploying - Optimization with proven structure - Fundamental physics: the only computer that thinks like nature ### Slide 13: Keep learning. - END · 13 / 13 - A field still being built. Pick a thread and pull. - ▶ Quantum Computing Explained — YouTube - ▶ Shor's Algorithm — YouTube - REFS · NIELSEN & CHUANG · ARXIV:QUANT-PH · QUANTA MAGAZINE · GOOGLE QUANTUM AI BLOG ## Related Decks - [Neuromorphic Computing](https://shipslides.com/d/future-neuromorphic-computing) - [The Quantum Internet](https://shipslides.com/d/future-quantum-internet) - [AGI // The Most Consequential Question](https://shipslides.com/d/catalog-future-agi) - [BCI // Reading and Writing to the Brain](https://shipslides.com/d/catalog-future-bci)