Quantum/Machines/Jiuzhang 4.0
China · operational · Photonic
Jiuzhang 4.0
Jiuzhang 4.0 is a photonic quantum computer operated by USTC in China. Its physical qubit count has not been published. 6 sourced specs are in the spec sheet. 1 published benchmark or milestone record are listed below, each marked by who measured it.
USTC's Jiuzhang 4.0 photonic Gaussian boson sampler, posted to arXiv in August 2025, with 1024 squeezed input states, 8176 modes and up to 3050 detected photons. The authors say they outperform classical spoofing algorithms including a matrix-product-state method, and give 25.6 microseconds per sample. It is a special-purpose sampler without a qubit count, and a preprint status is all that the sources consulted confirm.
Spec sheet
Technical details as the builder or a paper states them, each with its own source. A blank is a fact we could not source, not a zero. Fidelity and coherence figures are in the benchmark table below.
| Spec | Value | Basis | Note | Source |
|---|---|---|---|---|
| Processor | Jiuzhang 4.0: 8176-mode spatial-temporal Gaussian boson sampler, four OPOs, 16 SNSPDs | Peer reviewed | Published in Nature 653, 687 (13 May 2026); SNSPDs have 93 percent average efficiency and 43 ns recovery; whole-system efficiency 51 percent. | arxiv.orgnature.com |
| Qubit type | Single-mode squeezed states from four optical parametric oscillators (1024 squeezed states); no qubits | Peer reviewed | OPOs are pumped by 1.6 ns pulses at 775.7 nm, filtered by cascaded unbalanced Mach-Zehnder interferometers. | arxiv.orgnature.com |
| Topology | Three 16-mode interferometers joined by two fibre delay-loop arrays (spatial-temporal hybrid encoding) | Peer reviewed | The two delay-loop arrays span 0 to 15 tau and 0 to 15 x 16 tau time bins; the system has 8176 output modes in total. | arxiv.orgnature.com |
| Native gates | None (not gate-based): programmable Gaussian boson sampling with SNSPD readout | Peer reviewed | Special-purpose sampler; the authors give 25.6 microseconds per sample. | arxiv.orgnature.com |
| Predecessor | Jiuzhang 3.0 | Independent | PostQuantum names Jiuzhang 3.0 as the predecessor. | postquantum.com |
| Roadmap | Authors say the circuit will allow control of 3D cluster states in the near future and paves the way to fault-tolerant photonic hardware | Peer reviewed | Authors' statement in the Aug 2025 preprint, quoted by PostQuantum; no dates or successor machine are given. | arxiv.orgpostquantum.com |
Milestone claims
- USTC: up to 3050 photons, 25.6 us per sample; authors claim >1e42 years for MPS spoofing on El Capitan (2025-08, peer reviewed) arxiv.orgpostquantum.com
Timeline
- 2025-08-12: Announced
- 2025-08: First operational
- 2025-08-12: Status checked: operational
More from USTC
- Jiuzhang 3.0 (operational)
- Zuchongzhi 3.0 (operational, 105 qubits)
- Zuchongzhi 3.2 (operational, 107 qubits)
Comparable photonic machines
Closest in physical qubit count within the same technology. Counts of different qubit types are not interchangeable across technologies.
| Machine | Operator | Qubits | Status |
|---|---|---|---|
| Lucy | CEA | 12 | operational |
| Xanadu Aurora | Xanadu | 12 | operational |
| ORCA PT-2 at NQCC | National Quantum Computing Centre | - | operational |
| Aegiq ARTEMIS at NQCC | National Quantum Computing Centre | - | operational |
| Quandela Belenos | Quandela | 12 | operational |
| Quandela Canopus | Quandela | - | planned |