Futurizonte Editor’s Note: From quantum leaps to quantum speedups. What’s next?
Google will likely announce quantum speedup and quantum supremacy has been proven using the random circuit selection problem. It is pretty clear that physics allows quantum speedup.
Will there be Quantum Manhattan Projects?
Phase 1a – Scale existing superconducting technology to 1000 or so non-error-corrected qubits.
Phase 1b – Try to get better qubits and couplers for lower error rate and improved speed for 10000+ non-error-corrected qubits
Phase 2 – Get as fast as possible to error-corrected qubits in the million to trillion qubit range.
State of Quantum Computing
There is already hundreds of millions of dollars going into quantum computing projects.
China has talked about putting tens of billions of dollars into quantum technology. This included quantum radar and not just quantum computing.
Current competitors like Intel, Google, IBM, Facebook and Microsoft are each spending tens of millions of dollars on quantum computing projects.
Will tens of billions of dollars get committed for focused quantum computing projects?
There would be billions needed for more basic research and development of more options to determine the best ways to scale the technology. However, the superconducting quantum processors share many of the lithography technology of regular semiconductor manufacturing. Most of the quantum computer projects have used older lithography equipment.
Alternative to Superconducting Qubits
The transmon qubit modality has shown tremendous progress over the last decade, but it has certain limitations.
A different strategy, which still relies on the transmon qubit modality, replaces the local flux control used in the tunable transmon qubits with local voltage control, by using superconductor-semiconductor-superconductor Josephson junctions. In such systems, a local electrostatic gate is used to tune the carrier density in the semiconductor region, resulting in a modified EJ. Such devices were first demonstrated in InAs nanowires proximitized by epitaxially-grown aluminum, forming the transmon qubit element in a cQED setup. Subsequently, improved coherence times as well as compatibility with large external magnetic fields were demonstrated. However, the need to individually place nanowires makes the path to larger devices within this scheme potentially difficult. Alternative demonstrations of such hybrid superconducting qubit systems have therefore used two-dimensional electron gases amenable to top-down fabrication, as well as graphene flakes proximitized by evaporated aluminum. The absence of local currents results in a decrease of the power that needs to be delivered onto the qubit chip, but at the cost of reintroducing some charge noise susceptibility through the gate.