Optimal Quantum Fourier Transform on Rigetti Hardware: Parity Twine and Native iSWAP Gates Unlock Maximum Efficiency
June 30, 2026
Following our recent announcement regarding record QFT process fidelities achieved on the IBM Heron r3 processor, we are pleased to share a second major result from our latest publication, “Demonstrating Record Fidelity for the Quantum Fourier Transform”. While the CZ-based quantum computer set a new benchmark in process fidelity, our work also demonstrates an optimal scaling of the Quantum Fourier Transform (QFT) implementation by utilizing the native iSWAP gates on Rigetti’s 84-qubit Ankaa-3 system.
Parity Twine meets iSWAP: A Mathematically Optimal QFT Implementation
The core of this efficiency lies in the Parity Twine network – an efficient record-setting architectural method designed to distribute qubit parity information across a processor using only local interactions. This strategy leads to the best-known implementations of cornerstone algorithms like the QFT or the Quantum Approximate Optimization Algorithm (QAOA). The fundamental building block of the Parity Twine is the double-CNOT gate.
On hardware platforms where the iSWAP gate is a native instruction – such as the Rigetti Ankaa-3 system – Parity Twine exploits the fact that the iSWAP is locally equivalent to a double-CNOT gate. The result: an optimal QFT implementation in terms of the scaling of two-qubit gates. No implementation of the QFT can outperform this configuration.
Our experiments on the Ankaa-3 system indicate a scaling improvement when using the iSWAP-based Parity Twine compared to a standard CZ instruction set.
Beyond QFT: Parity Twine as a Universal Building Block for Quantum Algorithms
The implications of Parity Twine extend beyond the Quantum Fourier Transform which served as a benchmark in this work. This technique is applicable to any quantum algorithm that relies on creating parity pair interactions, such as the Quantum Approximate Optimization Algorithm (QAOA).
The Parity Twine software framework including the compiler and its optimal implementation strategies are now broadly available online. Users are now able to generate these high-efficiency circuits for various hardware platforms. If you want to express your interest in being one of the first users to try the Parity Twine framework, let us know here.
We would like to thank the team at Rigetti Computing for providing access to their QPU and for their continued technical assistance. A special thank you goes to Yuvraj Mohan and Kyle Strand for their dedicated technical and administrative support throughout these experiments.
FAQ:
A fundamental quantum algorithm used as a building block in many key quantum applications, including Shor’s algorithm, quantum phase estimation, and a wide range of simulation tasks.
An architectural method developed by ParityQC that distributes qubit parity information across a processor using only local interactions. This quantum circuit implementation strategy leads to record-setting circuit metrics for important applications.
The iSWAP is a native two-qubit operation on Rigetti’s Ankaa-3 system and locally equivalent to a double-CNOT gate. This makes it ideal for Parity Twine and enables an optimal QFT implementation in terms of two-qubit gate scaling.
No. While the Quantum Fourier Transform (QFT) served as a benchmark, Parity Twine applies to any quantum algorithm that relies on parity pair interactions, including the Quantum Approximate Optimization Algorithm (QAOA). Furthermore, the QFT is an essential building block of cornerstone quantum algorithms like Shor’s algorithm, which has direct implications for cybersecurity.
A tool that makes these optimal implementation strategies broadly available across different hardware topologies, now available online. If you want to be one of the first users to try the Parity Twine framework, let us know here.
The full publication, “Demonstrating Record Fidelity for the Quantum Fourier Transform,” is available here.
