Quantum technology, and quantum computing in particular, promises to be a key driver of future economic opportunities and geopolitical advantage. A large number of quantum platforms are currently being pursued by developers around the globe, each with their own roadmap to scale-up their system and targeting a wide variety of high profile applications.  However all current developers still face significant challenges and the race remains open. What can be said to inform investment decisions and priorities along this journey?
 
This report adopts the benchmark of a system capable of using Shor’s algorithm to break RSA 2048 as the criteria against which to assess roadmap challenges. It argues that a system meeting this large scale test will be a strong contender to become the dominant quantum design, securing major economic advantages. We analyze the criteria required to assess roadmaps against this target, and develop a framework for how investments in this journey can be assessed.
 
To date, many quantum roadmaps have prioritized demonstrating short term incremental progress. We argue that long term investors should want to see the most difficult roadmap challenges targeted early, rather than left as issues for later stages of the journey. The inflection points this could unlock have the potential to accelerate the field.
 
Quantum Technology is the largest paradigm shift in a generation. Our most fundamental description of nature, quantum mechanics, unlocks completely new resources not available via any other existing technology: true randomness, superposition and entanglement. Ultimately quantum tech, including computing, communications and sensing, will have a wide impact across all industry sectors. It will strengthen and accelerate other deep tech sectors, including biotech, AI & machine learning, robotics, crypto, blockchain and space. 
 
Quantum computing (QC) is the most high profile sector of quantum technology. Quantum hardware itself is set to be comparatively slow compared to other modern computing hardware, but instead it gains its power from the unique algorithms it can implement. Benefiting from an exponentially expanded computational space and natively embodying the unique statistics of entanglement,  it promises to perform certain computations beyond those practical on any Turing machine (i.e. any conceivable conventional computer).  This is a new computing capability. The potential synergy it brings in simulating nature, quantum-simulating-quantum, is particularly compelling for many experts.
 
Many challenges remain. In particular, the power of intermediate scale quantum computers remains unproven. Some hope for significant commercial benefits with such systems. However, many believe that substantial benefits will require much larger systems. These will use quantum error correction (QEC) to deliver fault tolerant quantum computing (FTQC). Such devices will ultimately be capable of trillions of quantum operations (the teraQuop regime) and beyond. 
 
The NATO Innovation Fund (NIF) exists to help deep tech entrepreneurs in participating Allied Nations to tackle long term challenges such as this. It sees the quantum sector as a priority opportunity for such investment.  In joint work, GQI and NIF have developed an approach to evaluate long-term quantum developer roadmaps.
 
Shor’s algorithm for cryptanalysis provides a useful example of a well studied quantum algorithm with clear applications. Large scale quantum systems are expected to be able to break many of the public key cryptographic protocols in common use today in business and the Internet. We use the development of a cryptographically relevant quantum computer (CRQC), capable of breaking RSA 2048 encryption within a 1 day window, as a suitable benchmark against which to assess what it takes to create a truly large scale machine. Its significance however isn’t just in its own utility, but also as a marker for other applications that machines of this scale are expected to be able to realize.
 
This report discusses the challenges at different layers of the tech stack in detail.  We find that the baseline designs across all major qubit platform approaches still have many challenges to face. There are also potential disruptors, strategic questions or opportunities that could affect roadmaps across the sector.