Imaging single atom array by ORCA®-Quest for Neutral Atom Quantum Computing

The main goal of the quantum computing field is to create a large-scale and error-tolerant general purpose quantum computer. Quantum transcendence, which means a quantum computer exhibits superior computational power over a classical computer, has been achieved by Google with 53 superconducting qubits, but it is for a solution to a specific problem and is not to a general problem. To reach a large-scale general-purpose quantum computer, several approaches are being proposed (e.g., superconducting qubit, trapped ion qubit), but it has yet to be decided which one is the winner. A scientific camera is commonly used in a quantum computer with neutral atom, one of the most promising qubits. We interviewed Professor Takashi Yamamoto and Assistant Professor Toshiki Kobayashi of Osaka University, who are using ORCA-Quest for neutral atom quantum computing.

 

The benefits of ORCA-Quest for Neutral Atom Quantum Computing

In a neutral atom quantum computer, neutral atoms are trapped in vacuum with optical tweezers and aligned in a lattice. The use of a scientific camera is to see the fluorescence from each individual atom trapped in that lattice, and it can observe the position of trapped atoms and even their quantum states. A major requirement for a scientific camera is its low noise and high quantum efficiency to eliminate false positives, which means the camera misunderstands an atom emits fluorescence due to its low sensitivity even when there is no fluorescence from the atom. Since we use a light source that essentially emits single photons in the application, a special camera such as ORCA-Quest, which can take images in which the number of photons is counted one by one, would be very ideal.

Also, in order to perform error correction of qubits, another requirement for a camera is the camera must readout the state of the qubit as quickly as possible and some feedback must be applied immediately according to the state. In terms of data readout speed, a CMOS camera such as the ORCA-Quest is superior to a conventional CCD camera. 

 

I see that many people used EM-CCD cameras in their papers for neutral atom quantum computing, but recently I feel that more and more people are using sCMOS cameras because of their performance improvement. The technology of EM-CCD and sCMOS is advancing considerably, and quantum efficiency and noise performance of both cameras are in so high level. In this context, the deciding factor in choosing ORCA-Quest for our research was the photon number resolving (PNR) mode. We have high expectations for qCMOS technology because the PNR mode cannot be achieved with EM-CCD due to its sensor technology, and we believe it would be very interesting if we can find a way to effectively utilize the PNR mode.

Image example by ORCA-Quest

Experimental condition

Atom:Rb (Emission wavelength 780 nm)
Atom spacing:13 um
Scan mode:Ultraquiet scan mode
Binning:2x2
Exposure time:20 ms
Occupation probability of an atom in a lattice site : about 50 %

Single shot

Frame average (200 frame)

Intensity histogram of an atom at bottom-right lattice site (Intensity summation in 4x4 pixel ROI, 200 frame)

Osaka university logo

Future outlook of the research

As mentioned earlier, the main goal of the quantum computing field is to create a large-scale error-tolerant general-purpose quantum computer. An error-tolerant general-purpose quantum computer would be very large, and it is estimated that it would require about  atoms, depending on the algorithm and protocol. To reach this goal, it is believed that a single physical system is not sufficient, and a networked quantum computer that connects multiple physical systems by using quantum teleportation, a quantum state is transferred by using quantum entanglement, for which the Nobel Prize in Physics was awarded in 2022, is being promoted. Currently, we are in the process of working hard on the local atomic quantum computer part since no one has yet created a physical system for quantum computing, large enough to be a general-purpose quantum computer with error tolerance.

We believe that with the very large number of pixels of ORCA-Quest (4096 (H) x 2304 (V)), we will be able to capture about  atoms with a single camera. When we compared ORCA-Quest and EM-CCD by their simulation results of single atom array imaging presented by Hamamatsu, we felt that both looked good, but the deciding factor in the end was the future expectation of qCMOS technology, such as “photon number resolving” mode

Researcher Profiles

Prof. Takashi Yamamoto
Vice director, Center for Quantum Information and Quantum Biology (QIQB), Graduate school of engineering science, Osaka university

2003: Doctor of Science, Department of Evolutionary Studies of Biosystems, School of Advanced Sciences
Apr. 2003: JST-CREST research fellow, School of Advanced Sciences
Apr. 2004: Specially appointed research assistant, Graduate school of engineering science, Osaka university
Apr. 2007: Assistant professor, Graduate school of engineering science, Osaka university
Apr. 2011: Associate professor, Graduate school of engineering science, Osaka university
Oct. 2018: Current post
2020: Project manager, Moonshot Goal 6 “Quantum Cyberspace with Networked Quantum Computer”, Moonshot R&D Program, Cabinet Office/JST
Award : The MEXT Young Scientists’ Prize (2014), etc.

Dr. Toshiki Kobayashi
Assistant professor, Center for Quantum Information and Quantum Biology (QIQB), Osaka university

2017: Doctor of Science, Graduate school of engineering science, Osaka university
Apr. 2017: Research fellow, Security Research Laboratory, NEC Corporation
Apr. 2019: Specially appointed assistant professor, Center for Quantum Information and Quantum Biology (QIQB), Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka university
Apr. 2022: Current post

Product used in this case study

The C15550-20UP is the world's first camera to incorporate the qCMOS image sensor. The camera achieves the ultimate in quantitative imaging.

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