PsiQuantum

Photonic Founded 2016 Palo Alto, CA, USA

Overview

Fault-tolerant photonic quantum computer using silicon photonics. Targeting 1 million+ qubits with error correction. Not available publicly yet—building utility-scale system first.

Funding: Series E — $1B (BlackRock-led, Sep 2025) at $7B valuation. $2.1B+ total raised.
Website: https://www.psiquantum.com

Key Milestones

  • 2016: PsiQuantum founded by Jeremy O'Brien, Terry Rudolph, Pete Shadbolt, Mark Thompson
  • 2020: Raised $215M Series C (largest quantum funding round at the time)
  • 2021: Partnership with GlobalFoundries for silicon photonics manufacturing
  • 2023: Raised $450M Series D (valuation >$3B)
  • 2024: Construction of utility-scale facility announced

Technology: Silicon Photonics

PsiQuantum builds photonic quantum computers using silicon photonics manufacturing—the same process used for telecom chips. Key advantages:

  • Scalability: Leverage existing semiconductor fabs (GlobalFoundries)
  • Room temperature operation (photons don’t need cryogenics for storage)
  • Fault tolerance from day one: Skip NISQ era, build error-corrected system

Challenge: Photonic quantum computing requires millions of components (waveguides, detectors, switches). PsiQuantum bets that silicon photonics can manufacture at scale.

No Near-Term Systems

Unlike competitors (IBM, IonQ, Google), PsiQuantum has no publicly available quantum computer. The strategy: don’t release noisy systems; wait until fault-tolerant, utility-scale system is ready.

Timeline: First commercial system expected late 2020s.

Criticism: Unproven technology, long wait times, no intermediate validation.

Defense: NISQ systems have limited value; better to wait for fault tolerance.

Measurement-Based Quantum Computing

PsiQuantum uses fusion-based quantum computing: photonic cluster states with measurement-based gate operations. This avoids need for deterministic two-qubit gates (which are hard with photons).

Technical approach:

  • Generate entangled photon pairs
  • Fuse them into cluster states via measurements
  • Perform computation via further measurements

Error correction: Topological codes (surface codes) implemented via photonic architecture.

Massive Funding

PsiQuantum raised $665M—more than most quantum companies combined. Investors include:

  • Blackrock
  • M12 (Microsoft’s venture fund)
  • Baillie Gifford
  • RedPoint Ventures

Valuation: >$3B (unicorn status).

Risk: All funding goes toward building first system. If it fails, no revenue to fall back on.

Competitive Position

vs. Xanadu:
Both photonic. Xanadu: systems available now (near-term advantage). PsiQuantum: waiting for fault tolerance (long-term bet).

vs. Superconducting (IBM, Google):
PsiQuantum claims photonics will scale better long-term. IBM/Google have working systems now but face scaling challenges.

Market position: High-risk, high-reward. Either becomes industry leader with first fault-tolerant system, or burns $665M trying.

Applications (When Available)

PsiQuantum targets utility-scale quantum computing for:

  • Drug discovery (molecular simulation)
  • Materials science (catalyst design, battery optimization)
  • Cryptography (Shor’s algorithm for factoring)
  • Optimization (logistics, finance, energy grids)

Timeline: Commercial availability late 2020s (estimated 2028-2030).