NowScience explains why we need quantum computing, how it compares to classical computing and what is holding us back from using it
In a world where we are relying increasingly on computing, to share our information and store our most precious data, the idea of living without computers might baffle most people.
But if we continue to follow the trend that has been in place since computers were introduced, by 2040 we will not have the capability to power all of the machines around the globe, according to a recent report by the Semiconductor Industry Association. To prevent this, the industry is focused on finding ways to make computing more energy efficient, but classical computers are limited by the minimum amount of energy it takes them to perform one operation. This energy limit is named after IBM Research Lab's Rolf Landauer, who in 1961 found that in any computer, each single bit operation must use an absolute minimum amount of energy. Landauer's formula calculated the lowest limit of energy required for a computer operation, and in March this year researchers demonstrated it could be possible to make a chip that operates with this lowest energy.
It was called a "breakthrough for energy-efficient computing" and could cut the amount of energy used in computers by a factor of one million. However, it will take a long time before we see the technology used in our laptops; and even when it is, the energy will still be above the Landauer limit. This is why, in the long term, people are turning to radically different ways of computing, such as quantum computing, to find ways to cut energy use.
Will we ever have the amount of computing power we need or want? If, as Moore's Law states, the number of transistors on a microprocessor continues to double every 18 months, the year 2020 or 2030 will find the circuits on a microprocessor measured on an atomic scale. And the logical next step will be to create quantum computers, which will harness the power of atoms and molecules to perform memory and processing tasks. Quantum computers have the potential to perform certain calculations significantly faster than any silicon-based computer.
How do Quantum Computer Work?
This superposition of qubits is what gives quantum computers their inherent parallelism. According to physicist David Deutsch, this parallelism allows a quantum computer to work on a million computations at once, while your desktop PC works on one. A 30-qubit quantum computer would equal the processing power of a conventional computer that could run at 10 teraflops (trillions of floating-point operations per second). Today's typical desktop computers run at speeds measured in gigaflops (billions of floating-point operations per second).
Quantum computers also utilize another aspect of quantum mechanics known as entanglement. One problem with the idea of quantum computers is that if you try to look at the subatomic particles, you could bump them, and thereby change their value. If you look at a qubit in superposition to determine its value, the qubit will assume the value of either 0 or 1, but not both (effectively turning your spiffy quantum computer into a mundane digital computer). To make a practical quantum computer, scientists have to devise ways of making measurements indirectly to preserve the system's integrity. Entanglement provides a potential answer. In quantum physics, if you apply an outside force to two atoms, it can cause them to become entangled, and the second atom can take on the properties of the first atom. So if left alone, an atom will spin in all directions. The instant it is disturbed it chooses one spin, or one value; and at the same time, the second entangled atom will choose an opposite spin, or value. This allows scientists to know the value of the qubits without actually looking at them.
Simplified quantum computer by InaNutshell
How Quantum Computers will be employed
1. Safer airplanes—Lockheed Martin plans to use its D-Wave to test jet software that is currently too complex for classical computers.
2. Discover distant planets—Quantum computers will be able to analyze the vast amount of data collected by telescopes and seek out Earth-like planets.
3. Win elections—Campaigners will comb through reams of marketing information to best exploit individual voter preferences.
4. Boost GDP—Hyper-personalized advertising, based on quantum computation, will stimulate consumer spending.
5. Detect cancer earlier—Computational models will help determine how diseases develop.
6. Help automobiles drive themselves—Google is using a quantum computer to design software that can distinguish cars from landmarks.
7. Reduce weather-related deaths—Precision forecasting will give people more time to take cover.
8. Cut back on travel time—Sophisticated analysis of traffic patterns in the air and on the ground will forestall bottlenecks and snarls.
9. Develop more effective drugs—By mapping amino acids,for example, or analyzing DNA-sequencing data, doctors will discover and design superior drug-based treatments.
However as with all disruptive technologies its the ways we haven't imagined yet that will most likely have the biggest impact on our lives.