QPUStatus

IBM Fez

Superconducting Transmon • 156 Qubits • Heavy-Hex Lattice • Heron r2 • TLS Mitigation • IBM Quantum System Two • First Heron r2 (Jul 2024)
IBM QUANTUM PLATFORM
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IBM offers dedicated reservation windows for enterprise clients via IBM Quantum Premium Plan. Reserved session telemetry is planned for future integration.
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ibm_fez is a cloud-access system hosted within an IBM Quantum Data Center. It is not available as a standalone on-premises deployment for third parties.

Live Status: Currently, the IBM Fez is Online via IBM Quantum Platform (0 jobs). Updated real-time for IBM Quantum circuit monitoring.

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IBM Quantum Platform

*Metric: Total number of jobs pending execution (Queue Depth) on ibm_fez via IBM Quantum Platform.

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Reserved Session Telemetry Coming Soon

On-Premises

Not Applicable for ibm_fez

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Hardware Deep Dive

IBM Fez (ibm_fez) was the first IBM quantum system to run the Heron r2 processor, introduced in July 2024. Heron r2 retains the 133-qubit Heron r1 architecture's tunable couplers and heavy-hexagonal layout but expands the qubit count to 156 and introduces a significant new capability: two-level system (TLS) mitigation. Two-level systems are microscopic material defects within the chip substrate and Josephson junction interfaces that can behave as spurious quantum systems, coupling to the computational qubits and reducing their coherence. Heron r2 actively monitors and adjusts the TLS environment, improving coherence stability across the whole chip over time. Together with software upgrades to the Qiskit runtime that introduced parametric compiling and optimised data movement, ibm_fez was the first system capable of accurately executing circuits with up to 5,000 two-qubit gate operations, a milestone IBM had set as its "100x100 challenge" in 2022. IBM reported a benchmark workload that previously took 122 hours on its best 2023 hardware completed in approximately 2.4 hours on ibm_fez, representing roughly a 50-fold speedup.

Technical Specifications

Architecture Fixed-Frequency Superconducting Transmon
Processor Family Heron r2 Source
Physical Qubits 156 Source
Topology Heavy-Hexagonal Lattice (max 3 neighbors per qubit)
Native Gates CZ, ID, RZ, SX, X Source
Tunable Couplers Yes — suppresses crosstalk to <0.1% level
TLS Mitigation Yes — controls the chip's TLS environment for improved coherence stability Source
Median 2Q Gate Error ~3×10−3 (best edge: ~1×10−3) Source
Max Two-Qubit Gates 5,000 (verified at 100-qubit, depth-100 circuit scale) Source
CLOPS 150,000+ (at launch, November 2024) Source
Median T1 / T2 ~100–200 µs / ~50–150 µs Source
Operating Temperature ~15 millikelvin (dilution refrigerator)
System IBM Quantum System Two
Introduced July 2024 (first Heron r2 deployment) Source
Cloud Access IBM Quantum Platform (IBM Cloud) via Qiskit SDK

Common Provider Questions

What is TLS mitigation and why does ibm_fez have it when ibm_torino does not?

Two-level systems (TLS) are microscopic material defects in the chip substrate and Josephson junction interfaces that can behave as spurious quantum systems. When a TLS energy level drifts close to a qubit frequency, it couples to that qubit and causes sudden drops in coherence time. On Heron r1 (ibm_torino) this was a known but unmitigated source of noise. Heron r2, first deployed on ibm_fez, introduced an active TLS mitigation scheme: the system continuously monitors the TLS environment and makes calibration adjustments to keep the chip operating away from TLS resonances. IBM's documentation describes this as controlling the TLS environment of the chip to improve coherence and stability across the whole device, which is particularly valuable for long, iterative circuits that benefit from consistent gate fidelity across many repeated executions.