Top Quantum Computing Stocks by Market Cap

1. Quantinuum (QNT) — $21.69B

Quantinuum develops trapped-ion quantum computers and quantum software, spun out of Honeywell in 2021. Its H-Series and Helios systems hold world records in gate fidelity and quantum volume. Software platforms include InQuanto (quantum chemistry), Quantum Origin (cybersecurity entropy), and lambeq (quantum NLP/AI). IPO: Nasdaq June 2026.

2. IonQ (IONQ) — $18.24B

IonQ develops trapped-ion quantum computers accessible via cloud through AWS Braket, Azure Quantum, and Google Cloud. The company builds full-stack quantum hardware and software targeting fault-tolerant quantum computing.

3. D-Wave Quantum (QBTS) — $8.35B

D-Wave is the world's first commercial quantum computing company, specializing in quantum annealing technology for optimization problems. Its systems are used in logistics, finance, and drug discovery.

4. Rigetti Computing (RGTI) — $5.97B

Rigetti Computing is a full-stack quantum-classical computing company using superconducting qubits. It fabricates its own chips at Fab-1 and provides cloud access through Quantum Cloud Services (QCS).

5. IQM Quantum Computers (IQMX) — $3.65B

IQM Quantum Computers is Europe's largest quantum computing hardware company, building on-premises superconducting quantum computers for national labs, HPC centers and universities — with systems delivered across Finland, Germany, Spain, Poland, South Korea, Taiwan and beyond. It operates its own chip fabrication facility in Espoo, Finland.

6. Xanadu (XNDU) — $3.51B

Xanadu is a photonic quantum computing company developing room-temperature, light-based quantum computers and open-source quantum software. Its Aurora system (Jan 2025) is the world's first scalable modular photonic quantum computer. PennyLane is the leading open-source quantum ML library.

7. Infleqtion (INFQ) — $2.69B

Infleqtion (formerly ColdQuanta) designs and builds quantum computers, precision sensors, and quantum software using cold atom and neutral atom technology. Its Sqale quantum computer has been commercially deployed at the UK National Quantum Computing Centre.

8. Quantum Computing Inc (QUBT) — $2.11B

Quantum Computing Inc develops photonic quantum processors and reservoir quantum computing systems. Its Dirac series uses Entropy Quantum Computing (EQC) for constrained optimization, and its Neurawave product applies photonic reservoir computing to edge AI inference.

9. Horizon Quantum (HQ) — $1.25B

Horizon Quantum builds quantum software infrastructure — compilers, development tools, and hardware-agnostic abstraction layers. Its Triple Alpha IDE and Helium language translate classical C/Python code into quantum-accelerated applications. Operates Singapore's first commercially deployed quantum computer as a software testbed.

10. Arqit Quantum (ARQQ) — $366.92M

Arqit provides quantum-safe encryption-as-a-service via its SKA-Platform, delivering symmetric key agreements resistant to both current and future quantum computer attacks, protecting governments and enterprises.

11. Quantum-Si (QSI) — $207.31M

Quantum-Si is building a semiconductor chip-based platform for single-molecule protein sequencing using quantum-detection technology. Its Platinum Pro system targets proteomics research; next-gen Proteus instrument targets late 2026 commercial launch.