*If you think you understand quantum mechanics, you don’t understand quantum mechanics*

Richard Feynman

All of three of these markets have the *potential* for being disruptive. In time Quantum *computing* could obsolete existing cryptography systems, but viable commercial applications are still speculative. Quantum *communications *could allow secure networking but are not a viable near-term business. Quantum *sensors *could create new types of medical devices, as well as new classes of military applications, but are still far from a scalable business.

It’s a pretty safe bet that 1) the largest commercial applications of quantum technologies won’t be the ones these companies currently think they’re going to be, and 2) defense applications using quantum technologies will come first. 3) if and when they do show up they’ll destroy existing businesses and create new ones.

We’ll describe each of these market segments in detail. But first a description of some quantum concepts.

Skip this section if all you want to know is that 1) quantum works, 2) yes, it is magic.

**Quantum ** – The word “Quantum” refers to quantum mechanics which explains the behavior and properties of atomic or subatomic particles, such as electrons, neutrinos, and photons.

**Quantum Computers – Background**

Quantum computers are a really cool idea. They harness the unique behavior of quantum physics—such as superposition, entanglement, and quantum interference—and apply it to computing.

In a classical computer transistors can represent two states – either a 0 or 1. Instead of transistors Quantum computers use quantum bits (called *qubits.) Qubits *exist in *superposition* – both in 0 and 1 state simultaneously.

Classic computers use transistors as the physical building blocks of logic. In quantum computers they may use trapped ions, superconducting loops, quantum dots or vacancies in a diamond. The jury is still out.

In a classical computer compute-power increases linearly with the number of transistors and clock speed. In a Quantum computer compute-power increases exponentially with the addition of each logical qubit.

But qubits have high error rates and need to be ultracold. In contrast classical computers have very low error rates and operate at room temperature.

Finally, classical computers are great for general purpose computing. But quantum computers can theoretically solve *some *complex algorithms/ problems exponentially faster than a classical computer. And with a sufficient number of logical Qubits they can become a *Cryptographically Relevant Quantum Computer* (CRQC). And this is where Quantum computers become very interesting and relevant for both commercial and national security. (More below.)

Quantum computers could *potentially* do things at speeds current computers cannot. Think of the difference of how fast you can count on your fingers versus how fast today’s computers can count. That’s the same order of magnitude speed-up a quantum computer could have over today’s computers for certain applications.

When you remove all the marketing hype, the only type that matters is #4 – a Universal Quantum Computer. And we’re at least a decade or more away from having those.

*Quantum Emulator/Simulator *These are classical computers that you can buy today that simulate quantum algorithms. They make it easy to test and debug a quantum algorithm that someday may be able to run on a Universal Quantum Computer. Since they don’t use any quantum hardware they are no faster than standard computers.

However, while all of these algorithms *might* have commercial potential one day, no one has yet to come up with a use for them that would radically transform any business or military application. Except for one – and that one keeps people awake at night.

** Impact of a Cryptographically Relevant Quantum Computer (CRQC) **Skip this section if you don’t care about cryptography.

Not only would a Universal Quantum Computer running Shor’s algorithm make today’s public key algorithms (used for asymmetric key exchanges and digital signatures) useless, someone can implement a “harvest-now-and-decrypt-later” attack to record encrypted documents now with intent to decrypt them in the future. That means everything you send encrypted today will be able to be read retrospectively. Many applications – from ATMs to emails – would be vulnerable—unless we replace those algorithms with those that are “quantum-safe”.

When Will Current Cryptographic Systems Be Vulnerable?

*Post-Quantum / Quantum-Resistant Codes*

That means if you want to protect the content you’re sending now, you need to migrate to new Post-Quantum /Quantum-Resistant Codes. But there are three things to consider in doing so:

Estimates of when you can actually buy a fully error-corrected quantum computers vary from “never” to somewhere between 8 to 20 years from now. (Some optimists believe even earlier.)

Quantum communications **≠** quantum computers. A quantum network’s value comes from its ability to distribute entanglement. These communication devices manipulate the quantum properties of photons/particles of light to build Quantum Networks.

*Quantum Random Number Generators (GRGs) *Commercial Quantum Random Number Generators that use quantum effects (entanglement) to generate nondeterministic randomness are available today. (Government agencies can already make quality random numbers and don’t need these devices.)

Random number generators will remain secure even when a Cryptographically Relevant Quantum Computer is built.

Quantum sensors **≠** Quantum computers.

*Quantum Timing *First-generation quantum timing devices already exist as microwave atomic clocks. They are used in GPS satellites to triangulate accurate positioning. The Internet and computer networks use network time servers and the NTP protocol to receive the atomic clock time from either the GPS system or a radio transmission.

These new sensors use a variety of quantum effects: electronic, magnetic, or vibrational states or spin qubits, neutral atoms, or trapped ions. Or they use quantum coherence to measure a physical quantity. Or use quantum entanglement to improve the sensitivity or precision of a measurement, beyond what is possible classically.

Gravimeters or quantum magnetometers could also detect concealed tunnels, bunkers, and nuclear materials. Magnetic resonance imaging could remotely ID chemical and biological agents. Quantum radar or LIDAR would enable extreme detection of electromagnetic emissions, enhancing ELINT and electronic warfare capabilities. It can use fewer emissions to get the same detection result, for better detection accuracy at the same power levels – even detecting stealth aircraft.

**Lessons Learned**