The U. S. Army Research Office (ARO) in collaboration with the Laboratory for Physical Sciences (LPS) is soliciting proposals for research in the next New and Emerging Qubit Science and Technology (nextNEQST) program.

nextNEQST focuses on qubit systems that explore new operating regimes and environments,

credit: IDEO

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fundamentally new methods of fabrication, and new methods of design, control, or operation.

These explorations should have in mind the development of quantum computation where the novel properties of these systems create significant advantages in coherence, fabrication, and/or qubit operation over current state-of-the-art qubits.A.

1. 1 Outline of the nextNEQST Research Areas:nextNEQST is soliciting proposals in three research areas as well as advances from previous NEQST research topics.

Proposals may address more than one of these research areas and, in some cases, may be required to address more than one area to achieve proposed research milestones.

Quantum information science and technology has seen steady progress since the motivating algorithmic discoveries of Shor and others.

Continued research in qubit technology has resulted in the development of several different qubit modalities that can now perform two-qubit operations with less than 1% error per gate, with advances towards higher performance and larger qubit systems on the horizon.

Many advances are needed to push existing technologies towards the distant goal of fault-tolerant quantum computing or systems of similar complexity.

This BAA anticipates that state-of-the-art qubit devices and quantum logic gate approaches, even with anticipated advances, may not be the same devices on which future technology will be based.

In other words, tomorrow's fault-tolerant quantum computers will not be made with today's qubits.

The nextNEQST program seeks to fund high-risk seedling efforts that can significantly advance the performance of future multi-qubit information processors towards the goal of fault-tolerant quantum computing.

Each effort should pursue the experimental realization of the proposal.

In addition, theory or model development must be included to elucidate the underlying mechanisms, and the theoretical and practical limits.

At the end of this three-year program, research progress will be evaluated to determine whether graduation to a larger research effort is warranted or whether the research direction should be abandoned.All proposals must address the following questions or subset of questions that are relevant to the proposed research:
1. What is the physical qubit(s) or quantum system that is being proposed? 2. What are the compelling reasons for using this qubit or system'? 3. What is known about this qubit in terms of experimental and theoretical results?Please provide suitable references.

4. What are the appropriate metrics for the novel technology 5. What limits do prior experimental or theoretic results place on the extremum of these metrics and how do these metrics relate to more traditional qubit performance metrics such as gate fidelity? 6. What are the challenges associated with fabricating and operating this qubit(s)? 7. What solutions are being suggested to overcome these challenges? 8. What is the timescale needed to demonstrate these solutions? 9. Are special experimental and fabrication resources needed?1 0. Are supporting technologies readily available?All proposals must set aggressive yearly quantitative milestones that define a path toward demonstrating the performance of the proposed qubit system, with comparison to the current state-of-the-art.A.

1. 2 New qubit, operating regimes, and environmentsThis research topic seeks exploration of new qubit and gate types that may enable relaxed environmental control requirements or fundamentally higher-fidelity operation.

New qubit systems insufficiently explored or not explored yet are one possibility.

Another is qubits that operate robustly (both alone and via two qubit gates) in “friendlier” environments such as at higher temperatures, pressures, or magnetic fields which could enable cheaper or more portable or more scalable quantum devices, from repeaters to sensors to quantum computers.

Proposals under this topic must articulate specifics of the novel physical system:
what are the advantages over current state-of-the- art qubit systems? why those advantages are important technical challenges to matching and surpassing current best qubit performance? and how one would attempt to construct, control, and isolate the novel system? There must be no fundamental roadblocks to constructing quantum processors with the selected qubit.

It is expected that some of the underlying physics may not be well understood, such as decoherence and coupling mechanisms.

The proposal should address this, and analysis should motivate later or follow-on experimental efforts to quantify current unknowns.

In particular, any proposals for investigation of new qubit systems must robustly address the question or fast and reliable two-qubit interactions (gates) as well as initialization and readout.A.

1. 3 Fundamentally new methods of fabricationThis research topic seeks proposals on new methods of fabrication that may enable new qubit types with superior performance.

For example, the perennial problem of noise might be solved by fully epitaxial fabrication techniques that could also enable new types of devices from epitaxial Josephson junctions to superconducting-semiconductors (super-semi) to engineered quantum materials.

In addition, new methods or fabrication may be required to achieve the promised performance of the proposed qubit type proposed in area A.

1. 2. A particular area of interest considers novel methods of fabricating planar semiconductor and superconductor qubits.

Also of interest are novel material systems for enhanced performance and/or addition of functionality.

Proposals under this topic must demonstrate fabrication of qubits and measure key qubit performance metrics along the way to a functioning qubit.

Before the end of the proposed research effort, modeling or simulation work should attempt to quantify the expected benefits in an idealized case, using a simplified or approximate system if necessary.A.

1. 4 New methods of design, control, or operationThis research topic seeks proposals based around design principles that enable easier or new means of control of multi-qubit systems.

Example research areas include super-semi junctions, which can be gated by an electrostatic potential, use of quantized / discretized control fields instead of classical control fields, topologically-motivated symmetry protection for physical devices, optical-based classical control of solid-state qubits (via classical transduction to electrical signals, for example), or other types of qubits and qubit/control combinations which reduce the complexity of classical control.

These qubits may enable simpler forms of control with less overhead or reliance on available control technology (i.e.

microwave generators or layers of error correction).

Proposals under this topic must demonstrate control of qubits and measure qubit performance along with key performance metrics along the way.A.

1. 5 Advanced NEQST researchPrevious research in NEQST research topics have made significant advances in 2-D materials, epitaxial qubit fabrication, and novel qubit design for error protection.

This topic seeks proposals in these NEQST research areas to advance state-of-the-art.

Proposals should explain why results-to-date or “lessons learned” are sufficiently promising to warrant next steps in demonstrating qubit operations.

Proposals must put previous results into the proper theoretical context and include improvements to simplified, ad-hoc, or phenomenological models if such are used.

These proposals must address the goal of realization of functional qubits and are expected to demonstrate full qubit operation and gate characterization by the end of the program.A.

1. 6 Topics Outside of Scope of nextNEQST 1. Bulk/ensemble systems without single qubit addressability.

2. Purely theoretical investigations of a proposed novel qubit.

3. Quantum transduction such as wavelength conversion in the quantum regime.

4. Quantum communication, networking, and key distribution.

5. Quantum computing architectures, error correction, and logical qubits beyondconsiderations given to scaling to approximately 10 qubit devices.

6. Approaches other than the circuit model of computation.