A breakthrough in quantum global gate clusters: a high-resolution iToffoli gate

A breakthrough in quantitative global gateway clusters: iToffoli HD Gateway

Experimental schematic of a high-resolution iToffoli gate in an advanced quantum test. Credit: Yosep Kim / Berkeley Lab

High-precision quantum logic gates applied to quantum bits (qubits) are the building blocks of programmable quantum circuits. Researchers in the Advanced Quantum Test (AQT) at Lawrence Berkeley National Laboratory (Berkeley Lab) have performed the first demonstration of the original 3-qubit iToffoli gate in a superconducting quantum information processor in a single step.

Noisy mid-size quantum processors typically support one or two native qubit gates, the types of gates that can be implemented directly by hardware. More complex gates are implemented by splitting them into sequences of original gates. The team’s demo adds a new, powerful three-qubit iToffoli gate for end-to-end quantum computing. Furthermore, the team demonstrated a high-accuracy gate operation of 98.26%. The team’s beta hack was posted at Nature Physics This is possible.

Quantum logic gates, quantum circuits

The Toffoli or Controlled NOT (CCNOT) is a major logic gate in classical computing because it is universal, so it can build all logic circuits to compute any desired binary operation. Moreover, it can be reversed, allowing binary inputs (bits) to be identified and retrieved from the output, so no information is lost.

In quantum circuits, the input qubit can be in a state of superposition of 0 and 1. The qubit is physically bound to other qubits in the circuit, making it more difficult to implement a high-precision quantum gate as the number of qubits increases. The fewer quantum gates needed to compute an operation, the shorter the quantum circuit will be, thus improving the algorithm’s execution before decoding the qubits causing errors in the final result. Therefore, reducing the complexity and operating time of quantum gates is critical.

Together with the Hadamard gate, the Toffoli gate forms a universal quantum gate assembly, which allows researchers to run any quantum algorithm. Experiments that have implemented multi-qubit gates in major computing techniques—superconducting circuits, trapped ions, and Rydberg atoms—have successfully demonstrated Toffoli gates on triple qubit gates with average fidelity between 87% and 90%. However, such demonstrations have required researchers to deconstruct Toffoli gates into gates with one or two qubits, making the gate run longer and reducing their loyalty.

A breakthrough in quantitative global gateway clusters: iToffoli HD Gateway

Researcher Yosep Kim pre-installing a superconducting QPU for experiment in the Advanced Quantum Testbed. Credit: Yosep Kim / Berkeley Lab

Create a portal that is easy to implement

To create an easy-to-implement three-qubit gate for the experiment, AQT designed an iToffoli gate in place of the traditional Toffoli gate by applying simultaneous microwave pulses stabilizing at the same frequency to three superconducting qubits in a linear series.

Similar to the Toffoli gate, the experiment showed that this three-qubit iToffoli gate can be used to perform a global quantum computation with high accuracy. Furthermore, the researchers show that mapping gates on superconducting quantum processors can produce additional triple-qubit gates, which provide more efficient synthesis of gates—the process of breaking quantum gates into shorter gates to improve circuit operating times.

Yosip Kim, one of the eminent researchers in the experiment and a former postdoc at AQT, is currently a senior scientist at the Korea Institute of Science and Technology (South Korea).

“As a result of decoherence, we know that longer and more complex gate sequences are detrimental to the accuracy of the results, so the total gate runtime for executing a particular algorithm is important. The show demonstrated that we can implement a three-qubit gate in one step and reduce the circuit depth (length of the gate sequence) for fitting the gate. So, unlike previous methods, our gate scheme does not include the higher-excitation states of the qubits subject to decoherence, resulting in a high-resolution gate, Kim said.

“I continue to be very impressed with the simplicity and sincerity of this iToffoli gateway,” Alexis Morvan said. “Now, using a three-qubit process like the one at work can greatly speed up quantum application development and quantum error correction.” A former postdoctoral researcher at AQT, he is currently a researcher at Google.

A breakthrough in quantitative global gateway clusters: iToffoli HD Gateway

Researcher Josip Kim checks the high-resolution iToffoli gate process in an advanced quantum test. Credit: Yosep Kim / Berkeley Lab

Benefit from the latest collaborative research lab

AQT is the latest collaborative research laboratory for quantum information science funded by the US Department of Energy, the US Department of Energy’s Advanced Scientific Computing Research Program. The lab is working on Open Access Beta Test Designed for deep collaboration with Berkeley Lab researchers and external users from academia, national laboratories, and industry. These interactive collaborations enable extensive exploration of the latest science in the AQT superconducting platform that relies on high-quality qubits, gates, and error mitigation while simultaneously preparing new generations of researchers in the field.

“I studied quantum information science using a photonics system during my Ph.D., so I didn’t have good knowledge to conduct the experiment in a superconducting processor,” Kim recalls. But since the base of beta testing is very well established and there are many multidisciplinary colleagues who know the setup work and have collaborated on the experiment, I was able to jump into the experiment very quickly with no prior experience. Without the AQT platform and team, I don’t think my ideas would have been realized at such a high level.”

“AQT provides researchers and users with a great opportunity to collaborate with people who come from different backgrounds and have diverse interests. This iToffoli project is one example of cross-pollination of ideas. Therefore, in addition to the spirit of scientific freedom at AQT, our work has also been accelerated by well-established infrastructure and continuous calibration , which allowed us to focus on the physics of our specific project without cutting out peripheral tasks.Moreover, the advanced control group enabled us to explore all possible applications for creating new quantum protocols,” said Long Nguyen, a current postdoctoral researcher at AQT.

The researchers hope that experimental approaches to high-resolution, easy-to-implement multi-qubit gates, such as those explored in the AQT, will lead to further studies to inventqubit Gateways for processing new quantum information.


Experimentally demonstrated a toffoli gate in a three-qubit semiconductor system


more information:
Yosep Kim et al, A high-resolution three-qubit iToffoli gate for superconducting qubits at a fixed frequency, Nature Physics (2022). DOI: 10.1038 / s41567-022-01590-3. www.nature.com/articles/s41567-022-01590-3

the quote: Breakthrough in Quantum Global Gateway Groups: iToffoli High Resolution Gateway (2022, May 24) Retrieved May 25, 2022 from https://phys.org/news/2022-05-breakthrough-quantum-universal-gate-high-fidelity .programming language

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