How to Connect Quantum Computer Bits with a Superconducting Circuit
This patent describes a superconducting circuit called an rf-SQUID that can precisely turn on, turn off, or change the way two quantum computer bits (qubits) interact with each other.
Original patent title: “Systems, devices, and methods for controllably coupling qubits”
This patent describes a superconducting circuit called an rf-SQUID that can precisely turn on, turn off, or change the way two quantum computer bits (qubits) interact with each other. Owned by Individual with 25 claims and 57 forward citations, and it is expected to expire in 2028.
Coverage
What does this patent actually cover?
This system provides a way to controllably link two quantum bits, or qubits, using a special superconducting loop called an rf-SQUID (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1). This rf-SQUID has a 'compound Josephson junction' and is connected to both a first qubit and a second qubit through magnetic fields (mutual inductance). A separate 'magnetic flux inductor' is also connected to the Josephson junction (Claim 1). By adjusting the magnetic field produced by this inductor, the system can control how the two qubits interact, allowing for different 'coupling states' such as anti-ferromagnetic coupling, ferromagnetic coupling, or even no coupling at all (Claim 3, Claim 5). For example, if you want two qubits in a quantum computer to perform a calculation together, this system could turn on their interaction, and then turn it off when they need to operate independently.
The gap
What does this patent NOT cover?
- Does not cover qubit coupling systems that do not use an rf-SQUID as the intermediate coupling device.
- Does not cover coupling mechanisms that do not rely on mutual inductance between the rf-SQUID and the qubits.
- Does not cover control methods for qubit coupling that do not involve a magnetic flux inductor adjusting flux through a compound Josephson junction.
- Does not cover qubits that are not superconducting, as the claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more → specifically mention 'superconducting flux qubit' (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 2) and 'superconducting material' (Claim 1).
- Does not cover direct coupling between qubits without an intermediate tunable coupler.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The cleverness lies in using an rf-SQUID with a compound Josephson junction as a tunable intermediary, allowing a magnetic flux inductor to precisely switch and adjust the quantum mechanical coupling between two qubits from zero to ferromagnetic or anti-ferromagnetic states.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Superconducting quantum processors
Tunable couplers in quantum computing architectures
IBM Quantum computers
Google's Sycamore processor
Rigetti Computing quantum systems
Why it matters
The bigger picture
Controlling how qubits interact is fundamental to building functional quantum computers. This patent offers a precise method to switch and tune these interactions, which is essential for executing quantum algorithms and building scalable quantum processors. Without such control, qubits would either always interact or never interact, severely limiting the types of computations possible.
Filed
January 22, 2008
Market context
Who's building on this
Companies in this space
Major players in superconducting quantum computing, such as IBM, Google, and Rigetti, are actively developing and utilizing tunable qubit couplers. These companies continuously research and implement advanced coupling mechanisms to improve the performance and scalability of their quantum processors. The original assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, an individual, is not a known commercial entity in this space.
Market impact
This type of tunable coupler technology has been crucial for advancing multi-qubit superconducting quantum computers. It enabled the creation of more complex quantum circuits by allowing researchers to precisely control when and how qubits interact, which is vital for entanglement and executing quantum gates. This capability has become a foundational element in the development of modern quantum computing platforms, influencing the design and architecture of commercial quantum processors.
Claim 1 — Plain English
What this patent covers
This system provides a way to controllably link two quantum bits, or qubits, using a special superconducting loop called an rf-SQUID (Claim 1). This rf-SQUID has a 'compound Josephson junction' and is connected to both a first qubit and a second qubit through magnetic fields (mutual inductance). A separate 'magnetic flux inductor' is also connected to the Josephson junction (Claim 1). By adjusting the magnetic field produced by this inductor, the system can control how the two qubits interact, allowing for different 'coupling states' such as anti-ferromagnetic coupling, ferromagnetic coupling, or even no coupling at all (Claim 3, Claim 5). For example, if you want two qubits in a quantum computer to perform a calculation together, this system could turn on their interaction, and then turn it off when they need to operate independently.
The clever bit
The cleverness lies in using an rf-SQUID with a compound Josephson junction as a tunable intermediary, allowing a magnetic flux inductor to precisely switch and adjust the quantum mechanical coupling between two qubits from zero to ferromagnetic or anti-ferromagnetic states.
What it does not cover
- Does not cover qubit coupling systems that do not use an rf-SQUID as the intermediate coupling device.
- Does not cover coupling mechanisms that do not rely on mutual inductance between the rf-SQUID and the qubits.
- Does not cover control methods for qubit coupling that do not involve a magnetic flux inductor adjusting flux through a compound Josephson junction.
- Does not cover qubits that are not superconducting, as the claims specifically mention 'superconducting flux qubit' (Claim 2) and 'superconducting material' (Claim 1).
- Does not cover direct coupling between qubits without an intermediate tunable coupler.
Patent timeline
Application submitted to the patent office
Patent enters public domain
PatentBrief Score
Impact Score
Moderate
Citation count
35/40
Highly cited
Claim breadth
17/20
Very broad protection
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$150K – $479K
Midpoint $300K · 1.3 yr remaining · industry ×1.6
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
25 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Harris, R. G. How to Connect Quantum Computer Bits with a Superconducting Circuit (U.S. Patent No. 20,080,238,531). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/20080238531/systems-devices-and-methods-for-controllably-coupling-qubits
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How to Connect Quantum Computer Bits with a Superconducting Circuit cover?
This patent describes a superconducting circuit called an rf-SQUID that can precisely turn on, turn off, or change the way two quantum computer bits (qubits) interact with each other.
Who owns patent US 20080238531?
This patent is owned by Individual.
When does this patent expire?
This patent is expected to expire on January 22, 2028, when the invention enters the public domain.
What is patent US 20080238531 cited by?
This patent has been cited by 57 later patents that build on its ideas.
What problem does this patent solve?
Controlling how qubits interact is fundamental to building functional quantum computers. This patent offers a precise method to switch and tune these interactions, which is essential for executing quantum algorithms and building scalable quantum processors. Without such control, qubits would either always interact or never interact, severely limiting the types of computations possible.
What does this patent NOT cover?
Does not cover qubit coupling systems that do not use an rf-SQUID as the intermediate coupling device.
Same assignee
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