ResQuant

Arqit develops the QuantumCloud platform for quantum-safe encryption, creating symmetric encryption keys that are computationally secure against both classical and quantum attacks. Unlike quantum key distribution (QKD), Arqit's approach is software-based and can work over existing network infrastructure. The company is publicly listed and has government and defense customers, though its technology claims have faced skepticism from some cryptography experts.

ID Quantique is a pioneer in quantum-safe security, offering quantum random number generators (QRNGs) and quantum key distribution (QKD) systems commercially since the early 2000s. The company's Quantis QRNG chips are integrated into Samsung smartphones and SK Telecom infrastructure. ID Quantique's Cerberis QKD systems have been deployed in government and financial networks across Europe and Asia. Based in Geneva, the company is majority-owned by SK Telecom.

Spun out of Alphabet (Google's parent company) in 2022, SandboxAQ focuses on AI combined with quantum technologies (AQ = AI + Quantum). The company develops post-quantum cryptography solutions to protect organizations against future quantum attacks, and quantum sensing applications. Valued at $5.75 billion, SandboxAQ has rapidly become one of the highest-valued companies in the quantum-adjacent space, with a strong roster of ex-Google talent and enterprise customers across government and financial services.

Qunnect develops room-temperature quantum networking hardware, including quantum memories, frequency converters, and entanglement sources designed to operate in existing telecom infrastructure. Based in Brooklyn, NY, the company aims to enable quantum networks that connect quantum computers, sensors, and secure communication systems over fiber-optic cables without requiring cryogenic cooling at every node.