IP monitor: Early USPTO decision suggests favorable treatment for quantum computing

The Patent Trial and Appeal Board (PTAB) of the United States Patent and Trademark Office (USPTO) has recently issued what may well be its first decision about eligibility of quantum computing inventions to patent protection (addressing rejections under 35 U.S.C. § 101 and 35 U.S.C. § 112). While a single early decision can hardly be considered a trend, it does form a data point in a technological field set to constitute the next technological revolution, and it interestingly appears favorable to patenting quantum computing inventions.

The decision overview

The appeal decision in Ex parte Yudong Cao (Application No. US 16/591,239), dated February 11, 2025, concerns a patent application for a hybrid quantum-classical computer system designed to solve linear systems on noisy quantum computers that have limited circuit depth. 

The invention involves an iterative process with a classical computer generating an objective function, and a quantum computer i) preparing a quantum state according to a set of circuit parameters on a plurality of qubits and ii) performing an informed measurement. This measurement is then used to generate an estimate of the objective function, and the classical computer can then update the objective function based on the estimate, for the next iteration. 

The PTAB reversed the examiner's rejection to the effect that the claims were too “abstract” (i.e., under 35 U.S.C. § 101), aligning with the principles set forth namely in Alice Corp. Pty. Ltd. v. CLS Bank Int’l, 573 U.S. 208, 216 (2014). 

Claim interpretation and the decision

The examiner had determined that the step of “on a quantum computer, controlling a plurality of qubits, according to [a] set of circuit parameters, to prepare a quantum state was “a recitation of gathering data of a particular type or source to be used in performing the abstract idea.” 

On appeal, the PTAB disagreed with this finding, and indicated this latter element “represents the focus of the invention and integrates the recited abstract idea [of mathematical relationships] into a practical application[…] enabling noisy quantum computers, which have limited circuit depth, to practically solve linear systems - a technology improvement.” 

Drafting quantum computing patent applications to resist § 101 and § 112 rejections

In its decision, the PTAB explicitly noted the original specification of the patent application insisted on the existence of this problem on quantum computers, the need for a solution, and explicitly tied the teachings of the specification to a solution to that problem. The underlying drafting approach clearly favored the appellant in front of the PTAB, similarly to how this recommendable drafting approach has been known to help patent applications focused on classical computer-implemented processes to traverse examination. 

This decision may be cited by patent prosecutors when making arguments to the effect that steps involving applying quantum circuits to prepare quantum states should be considered to bring the claims into the realm of patent eligibility. 

This decision came against the backdrop of case law and practice procedures developed on classical algorithms operating on bits. There has been a trend where rejections essentially arguing that encoding information into bits are mental acts, insufficient in and of themselves, to bring an invention into the realm of patent eligibility. The decision does not specifically address whether encoding information into qubits, which can involve preparing a quantum superposition ‒ an action that is not replicable by the human mind ‒ would be sufficient, in and of itself, to bring the invention into the realm of patent eligibility. It will be interesting to see whether the next PTAB decision will address this point. 

The examiner had also argued the claim lacked written description. The PTAB sided with the appellant on this front, finding that an example of the broader class of “objective functions” had been provided in the original specification, and reminding the examiner in passing that sufficiency of support in the description is a question that must be considered from the point of view of persons having ordinary skill in the art (which is very specialized and learned in the context of quantum computing).

The presence of the underlying debate reminds patent prosecutors that providing several differing examples of elements that fall within a genus defined in the main claims is recommendable, when feasible. 

Conclusion

The USPTO's decision in Ex parte Yudong Cao sheds some light on, and represents an encouraging development for the quantum computing field, a technology sector expected to cause a major technological disruption in the near future. 

In an article published in 2024, McKinsey evaluated that quantum computing alone, just one of three main areas of emerging quantum technology, could account for nearly $1.3 trillion in value by 2035. In the context of Canada’s National Quantum Strategy, government officials indicated that, “According to a study commissioned by the National Research Council of Canada (NRC), the quantum sector will become a $139 billion industry in Canada with more than 200,000 jobs and $42 billion in returns by 2045, potentially contributing 3% to Canada's GDP.”  

By recognizing the unique nature of quantum algorithms and providing a pathway for their patentability, the USPTO is continuing the patent system’s primary purpose of incentivizing innovation and the public disclosure of inventions, granting innovators exclusive rights in exchange for making the inventions publicly available.

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