Comments about the article in Nature: How to introduce quantum computers without slowing economic growth

Following is a discussion about this article in Nature Vol 619 20 July 2023, by Chander Velu & Fathiro H.R. Putra
To study the full text select this link: https://www.nature.com/articles/d41586-023-02317-x

• The text in italics is copied from the article
  
• Immediate followed by some comments
  

In the last paragraph I explain my own opinion.

Contents

• 1. Demonstrate the value of quantum computers for societal challenges
• 2. Agree on a common language and build understanding
• 3. Build a quantum internet with secure encryption
• 4.

Reflection

• Reflection 1 -
• Reflection 2 -
• Reflection 3 -

Introduction

The breakthroughs they promise — new ways of simulating materials, optimizing processes and improving machine learning — could transform society, just as today’s digital computers have done.

The main problem is that the physics involved i.e., quantum mechanics, the study of elementary particles, contains many uncertainties.

The quantum computing revolution could be much more painful.

Probably true.

Quantum computers operate in a completely different way from digital computers, and can potentially store and analyse information more efficiently.

This still contains a risk.

Quantum computers encode information in the quantum state of atoms, electrons and photons, known as qubits. These qubits can represent many states at once and be combined or 'entangled’, thereby speeding up calculations.

That is theoretical a correct description, but contains a big if, if this physical goal can be reached in reality.
However IMO the biggest problem is to convert a physical process into QC logic, which can be implemented onto a QC, and be solved.
A simpler path to go is to start with a mathematical problem, but that limits its application space.

When digital computers started to gain popularity in the 1970s and 1980s, rather than delivering efficiencies, for 15 years they slowed growth in productivity, the value added relative to inputs such as labour, by 0.76 percentage points per annum.

Agreed

We think that the quantum computing revolution could lead to an even more severe and expensive learning curve, for three reasons:

1. high integration costs and few short-term rewards;
2. difficulty in translating quantum concepts for business managers and engineers;
3. and the threat to cryptography posed by quantum computers.

• Reason 1 can be expected for all drastically new inventions.
• Reason 2 is the most technical and the most drastic. This requires first to translate the description and solution of a problem into the (operating) language of a quantum computer. Secondly to understand that a quantum computer does not operate sequentieel but in parallel. Sequentieel means that each (small) task or step only starts when the previous task or step is finished. Parallel means that all the tasks or steps are executed simultaneous.
• Reason 3 works, funny, in both directions

Fortunately, there are ways to lighten the load and accelerate the benefits to society, three of which we outline here.

I'm pessimistic if quantum computers have benefits for all of us.

1. Demonstrate the value of quantum computers for societal challenges

Firms might initially adopt quantum computers to solve existing business problems, for which improvements are likely to be incremental. But for more-ambitious uses, the extra costs and likelihood of potential failures might make firms risk-averse.
For example, a company that collects vast amounts of data from sensors to inform disaster relief and recovery might look to quantum computers to process information more quickly, to help save lives.

When a disaster is in progress and lives are at stake, you need a rescue team, with experience and gouvermental support, to cross borders. I doubt if QC's will be of much help.

But the first such computers might be more prone to faults and errors than are digital ones, with potentially grave consequences for life-critical operations. Such companies might therefore be put off from using quantum computers, until they are more reliable.

The problem with quantum computers is that they work with propabilities. That means the result, based on the same data, is not always the same. Digital Computers don't work with probabilities. The answer is always the same. I can not estimate the severity of this problem

Firms will still need digital computers to perform everyday tasks and computations; they will use quantum computers to solve more-complex and specialist problems.

Remember, my expectation is, to solve complex computers on a QC, will be very tricky. Start simple.

Yet, developing hybrid protocols and programs that can work in both situations is much harder than it was to program digital computers in the 1970s.

In the 1970s the problem was related to Analog Computers versus Digital Computers.
The Analog Computer was, for example, used to simulate one specific airplane. The air plane was simulated as a set of differential equations.
The Digital Computer was used to set up the initial conditions of each run and the individual parameters.
The special interface between the DC and the AC to convert digital signals into analog signals and the reverse between the AC and the DC creates what is called a Hybrid Computer.

Hybrid systems will need to be fluent in both digital bits and quantum qubits, and able to encode classical data into quantum states and vice versa.

Hybrid systems in 2023 are a combination between a Quantum Computer and a Digital Computer. The QC is based around qubits. The DC is based around digital bits.

2. Agree on a common language and build understanding

Quantum technologies operate on principles that are often counterintuitive and outside the comfort zone of many engineers and business managers.

They should not be outside the comfort zone of physicists. Physicists should 100% agree on the principles Quantum computers are based upon.

For example, these technologies work probabilistically and don’t seem to obey classical conceptions of cause and effect.

We live in one world. It is wrong to speak of a classical world versus a quantum world. Every photon or neutrino that reaches the earth has an origin, is caused by something else in the past and is surrounded by a cloud of uncertainty.

According to some schools of thought, in the quantum world, human agency might influence outcomes, meaning the person operating the computer might need to be considered as part of the system.

I would like to ask the authers of this text (Heisenberg?) to explain what they mean.
We don't live in a quantum world. We humans are situated somewhere in the universe. The universe, enlarge, consists of objects based out of elements (atoms) and molecules. Humans, in general, are in no way, involved in the evolution of the universe.

Managers and engineers will need to know enough to be able to select the right class of problems for quantum computers, know what type of information is required to solve them, and prepare data in a quantum-ready format (see go.nature.com/3opfsap or: https://www.ft.com/content/b1f77666-53ab-4cfe-95ae-7945c2c8d13e ).

This is a very complex technical problem, which involves training.

For example, a delivery logistics company might wish to reschedule its vehicle routes more rapidly to respond better to customer demand for pickups of goods that need returning.

The question is simple, the answer can be difficult. The overall issue is, if it is possible.

Quantum computation could be effective for such replanning — which involves solving a complex combinatorial problem — in which one change has a knock-on effect on other areas of the business, such as inventory management and financing.

Could be.

But managers would need to be able to spot areas of advantage such as this and know what to do to implement quantum computing solutions.

You need qualified engineers, not managers.

A common semantic and syntactic language for quantum computers needs to be developed.

The question is easy . The actual solution is complex .

It should be similar to the standardized Unified Modeling Language used for digital computer programming — a visual language that helps software developers and engineers to build models to track the steps and actions involved in business processes.

https://www.uml.org/what-is-uml.htm
https://nl.wikipedia.org/wiki/Unified_Modeling_Language
https://www.nchsoftware.com/chart/index.html

My overall impression is, that in order to write a usefull program, much more detailed information is requiered.

Such a tool reduces the costs of software development by making the process intuitive for business managers.

Some people believe in dreams.

Quantum computers also require algorithms and data structures, yet quantum information is much richer than classical information and more challenging to store, transmit and receive.

First you must now exactly know, what an algorithm for a QC is.
My impression is that the logic behind an algorithm for a QC is something completely different than the logic behind an algorithm for a DC.
The logic behind a DC is sequential. To get an idea select this link: https://en.wikipedia.org/wiki/IBM_Quantum_Experience

A quantum unified modelling language that is similar to the classical one but can also work with quantum information will enable scientists, engineers and managers to stay on the same page while they discuss prototypes, test beds, road maps, simulation models and hybrid information-technology architectures

My impression that you need a complete new language and complete change of mind to use a quantum computer.

Strategies for communicating about quantum computing with the public are also needed, to build trust in these new technologies and ensure that benefits accrue to all parts of society in a responsible manner.

To build trust you need an easy to explain example that shows the advantage of a Quantum Computer versus a Digital Computer.
That is not easy

3. Build a quantum internet with secure encryption

Reflection 1 - The physics behind Quantum Computers

• Consider the following dangerous experiment.
  Take two jam jars. In both you put a frog. Close the lid of one jam jar.
  Intially the behaviour of both frogs will be the same. After a certain time the frog in the closed jar stops moving, and dies.
  Lesson learned: The life cycle of a frog is: To be alive, dying and dead.
• Consider the following dangerous experiment.
  Take two jam jars. Paint the outside of one jar black. In both you put a frog. Close the lid of both jam jars.
  After a certain time, I inform the audience: I will open both jars, but before I open the black painted jar, the frog is both (simultaneous, in a superposition state of) alive and dead.
  Next I open the jar and the two frogs are dead.
• In reality what I describe is the Schrödingers cat paradox, in a slightly different setting. See also: https://en.wikipedia.org/wiki/Schrödinger's_cat
  The reason of this dual experiment is to challenge the "Copenhage Interpretation" https://en.wikipedia.org/wiki/Copenhagen_interpretation which claims that the act of measuring/observing establishes the actual state of the frog.

  In the experiment with the frog or Schrödingers cat only one parameter of a physical process is measured. The point is that no human is actual involved with the evolution of this process. What I want to emphasize, that in this case, the observer can continuous monitor the state of the frog or at a specific instant. Secondly what the observer selects, has no physical influence on the evolution, what so ever. Even if this same process happens by accident, the evolution will be the same.
  What is even more important, that neither the frog nor the cat is ever in a superposition state of being both (simultaneous) alive and dead The frog is physical either: alive, or dying, or dead.

  But that is not always as simple. If you want to measure the speed always two measurements (events) are involved. You need the speed and the time of these two events, and a simple calculation to calculate the speed. But what you get is an average speed, assuming that the path is straight. In this case it is the operator who decides, but during this experiment no superpositions are involved.

  In the url referencing the Copenhage interpretation, mentioned above, two more concepts are mentioned: the (collapse of the) wave function and entanglement The most physical examples of waves are water waves. A water wave can be described as a cyclic phenomena and mathematically as a sinus function.

Reflection 2

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