Horizon Quantum Computing
Software-first quantum company building a hardware-agnostic IDE (Triple Alpha) and algorithm-synthesis compiler stack that converts classical source code into quantum programs. In December 2025 deployed Ember One — what the company described as the first quantum computer owned and operated by a quantum-software firm — a Singapore-deployed system integrating a Maybell cryogenic platform, Quantum Machines control electronics, and a Rigetti Novera superconducting QPU. Listed on Nasdaq as "HQ" in March 2026 via dMY Squared SPAC merger.
Timeline
Current flagship
Triple Alpha — hardware-agnostic quantum IDE with Helium / Hydrogen / Beryllium language stack; first in-house system "Ember One" (Rigetti Novera 9-qubit transmon)
Milestones
- 2026-03Nasdaq listing as "HQ" via dMY Squared SPAC merger; ~USD 120M raised at ~USD 503M valuation
- 2025-12Ember One activated — first commercial quantum computer in Singapore; what the company described as the first quantum computer owned and operated by a quantum-software firm (Maybell cryostat + Quantum Machines control + Rigetti Novera QPU)
- 2025-12Beryllium object-oriented quantum programming language debuted
- 2025-09dMY Squared business-combination agreement signed at USD 503M valuation
- 2023-03USD 18.1M Series A led by Sequoia Capital India, with Tencent, SGInnovate, Pappas Capital, Expeditions Fund
- 2020-06Seed-plus round (Sequoia Capital India-led) bringing seed total to SGD 4.5M (~USD 3.23M)
- 2018Founded in Singapore by Joe Fitzsimons (ex-SUTD); initial SGD 1.2M seed led by SGInnovate
Roadmap
Capability details
Quantum computing
- Qubit type
- transmon
- Physical qubits
- 9
- Logical qubits
- 0
- 1Q gate fidelity
- —
- 2Q gate fidelity
- —
- T₁
- —
- T₂
- —
- EC code
- —
- Connectivity
- square-lattice
14 unverified fields
-
modalities.qc.one_q_fidelity -
modalities.qc.two_q_fidelity -
modalities.qc.coherence_t1_ms -
modalities.qc.coherence_t2_ms -
modalities.qc.ec_code -
modalities.qc.gate_set -
modalities.qc.physical_qubits_current— 9 reflects Rigetti's Novera 9-qubit transmon chip (3×3 tunable-coupler lattice) that Horizon integrated into Ember One; Novera also ships a 5-qubit test die in the same puck but the 9-qubit die is the operational QPU. Horizon does not publish its own fidelity / coherence numbers — those depend on the as-installed Novera die and are not separately disclosed by Horizon -
modalities.qc.connectivity— Square-lattice with tunable couplers per Novera spec; Horizon has not published its own measured connectivity report -
shareholders— stakes are listed by class only; post-SPAC cap table (after the March 2026 Nasdaq listing) not yet cross-checked against an S-1 / F-4 / first 10-K filing -
key_personnel.2.since— CFO start date inferred from vendor About page presence; not explicitly dated -
key_personnel.3.since -
key_personnel.4.since -
key_personnel.5.since -
key_personnel.6.since
People
- Joe Fitzsimons — CEO & Founder (since 2018) ↗
- Si-Hui Tan — Chief Science Officer (since 2018) ↗
- Greg Gould — Chief Financial Officer (since 2024) ↗
- Raymond Lloyd — VP Engineering (since 2022) ↗
- Amanda Chew — VP Product (since 2022) ↗
- Eoin Scanlon — VP Operations (since 2022) ↗
- Denis Chevallier — Director of Hardware (since 2024) ↗
References
- press https://www.cnbc.com/2025/12/04/horizon-quantum-software-startup-deploys-singapores-first-quantum-computer-for-commercial-use.html CNBC coverage of Ember One deployment (Dec 2025)
- press https://thequantuminsider.com/2025/12/03/horizon-quantum-in-house-quantum-computer/ Quantum Insider on the in-house QC announcement; names the Maybell + Quantum Machines + Rigetti stack
- press https://quantumcomputingreport.com/horizon-quantum-becomes-first-quantum-software-company-to-own-and-operate-quantum-computer/ Quantum Computing Report on the Ember One system
- blog https://www.horizonquantum.com/triple-alpha Triple Alpha product page — IDE, compiler, Helium / Hydrogen language reference
- paper https://arxiv.org/abs/0807.4154 Broadbent, Fitzsimons, Kashefi — "Universal blind quantum computation" (FOCS 2009); foundational Fitzsimons paper on verifiable / blind QC
- paper https://arxiv.org/abs/1203.5217 Fitzsimons & Kashefi — "Unconditionally verifiable blind computation" (Phys. Rev. A 96, 012303, 2017)
- paper https://arxiv.org/abs/1512.04375 Fitzsimons & Hajdušek — "Post hoc verification of quantum computation"; methods that inform Horizon's verification-aware compiler thinking
- press https://thequantuminsider.com/2026/03/19/horizon-quantum-goes-public-via-spac-raises-120-million/ SPAC close and Nasdaq listing as "HQ" (March 2026)