Arqit Quantum

Arqit Quantum (Nasdaq: ARQQ) is a London-based quantum encryption technology company founded in 2017, publicly listed via SPAC merger in 2021, that has pivoted from satellite-based quantum key distribution (QKD) to software-defined symmetric key encryption — now positioned as a provider of post-quantum cryptography solutions for government, enterprise, and critical infrastructure customers seeking to protect data against future attacks from quantum computers capable of breaking current RSA and elliptic curve cryptography.

Arqit's original business concept was satellite-mediated QKD: launching satellites equipped with photon sources to distribute quantum encryption keys to ground stations using the fundamental physics of quantum mechanics (where any eavesdropping on photon transmission disturbs the quantum states, making interception detectable). Two quantum key distribution satellites were built with the European Space Agency and QinetiQ Space, but Arqit sold that business in May 2023 and the remaining contracts were transferred away in September 2024; it no longer has a satellite programme.

However, the company pivoted substantially from hardware QKD to software-based key agreement protocols, repositioning its QuantumCloud product as a symmetric key agreement system that can run on conventional infrastructure without satellite hardware dependency — a dramatically faster path to commercial deployment than manufacturing and launching dedicated quantum satellites.

The QuantumCloud service generates symmetric encryption keys (which quantum computers cannot break more effectively than classical computers, unlike asymmetric public key cryptography) through a software key derivation protocol, delivering these keys to devices via an authenticated cloud service. This approach is marketed as 'quantum safe' because it does not rely on factoring-hard or discrete-log-hard mathematical problems that quantum Shor's algorithm breaks.

The target use cases include government secure communications (agencies planning for post-quantum migration compliance with NIST PQC standards), enterprise VPN and cloud security, 5G network security, and critical infrastructure protection.

Arqit has faced significant scrutiny from short-sellers and analysts questioning the technical feasibility claims and financial sustainability of the original satellite QKD concept, contributing to a dramatic decline in stock price from peak SPAC valuations. The company's ~$200M market cap reflects ongoing investor skepticism. Competitors in post-quantum cryptography solutions include PQShield, evolutionQ, CryptoNext Security, and the major cloud providers (AWS, Azure, Google) implementing NIST-standardized PQC algorithms.