BEYOND BINARY- Quantum Computing
“A classical computation is like a solo voice — one line of pure tones succeeding each other. A quantum computation is like a symphony — many lines of tones interfering with one another.” — Seth Lloyd
The benefits of classical computers in our daily life seem endless. However, there are challenges that today’s systems will never be able to solve, at least not within a feasible time frame. We cannot use classical computers to tackle problems that have more than a certain level of complexity and size. To stand a chance at solving some of these problems, we need a new kind of computing.
Quantum computing is the use of quantum phenomena such as superposition and entanglement to perform computation. All computing systems rely on a fundamental ability to store and manipulate information. Current computers manipulate individual bits, which store information as binary 0 and 1 states. Quantum computers leverage quantum mechanical phenomena to manipulate information. To do this, they rely on quantum bits or qubits.
QUBITS — THE BUILDING BLOCKS OF QUANTUM COMPUTING
An ordinary computer chip uses bits. These are like tiny switches, that can either be in the off position (0) or in the on position (1). Every app you use, the website you visit, and the photograph you take is ultimately made up of millions of these bits in some combination of ones and zeroes.
Quantum computers, on the other hand, use qubits, which are typically subatomic particles such as electrons or photons. Generating and managing qubits is a huge scientific and engineering challenge. Some companies use superconducting circuits cooled to temperatures colder than deep space. Others trap individual atoms in electromagnetic fields on a silicon chip in ultra-high-vacuum chambers.
In both cases, the primary goal is to isolate the qubits in a controlled quantum state. Qubits have some quirky quantum properties that give them the advantage of speed over classical computers. One of those properties is known as superposition and another is called entanglement.
WHAT IS QUANTUM SUPERPOSITION?
Quantum superposition is a fundamental principle of quantum mechanics. It states that, much like waves in classical physics, any two or more quantum states can be added together, resulting in another valid quantum state.
Qubits can represent numerous possible combinations of 1 and 0 at the same time. This ability to simultaneously be in multiple states is called superposition. To put qubits into superposition, researchers have to manipulate them using precision lasers or microwave beams.
Thanks to this counterintuitive phenomenon, a quantum computer with several qubits in superposition can crunch through a vast number of potential outcomes simultaneously.
WHAT IS QUANTUM ENTANGLEMENT?
Researchers can generate pairs of qubits that are “entangled,” which means that the two members of a pair exist in a single quantum state. Changing the state of one of the qubits will instantaneously change the state of the other one in a very predictable way. This happens even if they are separated by very long distances.
Nobody really knows quite how or why entanglement works. But it’s a key phenomenon that gives quantum computers their power. In a conventional computer, doubling the number of bits doubles its processing power. But thanks to entanglement, adding extra qubits to a quantum machine produces an exponential increase in its number-crunching ability. This is what gives quantum computers their high-speed computation feature.
That’s the good news. The bad news is that quantum machines are way more error-prone than classical computers, because of something called quantum decoherence.
QUANTUM DECOHERENCE — A PROBLEM TO BE TACKLED
The quantum state of qubits is extremely fragile. The slightest vibration or change in temperature (called “noise” in quantum terms), can cause them to tumble out of superposition before their job has been properly done. This decay in quantum behavior due to external interaction is called decoherence. This is why qubits have to be isolated from the outside world in those supercooled fridges and vacuum chambers.
If a quantum system was perfectly isolated, it would maintain coherence indefinitely, but it would be impossible to manipulate or investigate it.
If it is not perfectly isolated, for example during a measurement, coherence is shared with the environment and appears to be lost with time, then quantum decoherence can be observed.
But despite all efforts, noise still causes lots of errors to creep into calculations. Sometimes, adding more qubits helps. However, it will likely take thousands of standard qubits to create a single, highly reliable one, known as a “logical” qubit.
And so far, researchers haven’t been able to generate more than 128 standard qubits (see our qubit counter here). So, we’re still many years away from getting quantum computers that will be broadly useful.
SOME BASIC APPLICATIONS OF QUANTUM COMPUTING
One of the first and most promising applications of quantum computing will be in the area of chemistry. Even for simple molecules like caffeine, the number of quantum states in the molecule can be astoundingly large — so large that all the conventional computing memory and processing power that could ever be built could not model it.
Quantum computers can be used for simulating the behavior of matter down to the molecular level. Auto manufacturers like Volkswagen and Daimler are using quantum computers to simulate the chemical composition of electrical-vehicle batteries to help find new ways to improve their performance. And pharmaceutical companies are leveraging them to analyze and compare compounds that could lead to the creation of new drugs.
The machines are also great for optimization problems because of their ability to crunch through vast numbers of potential solutions in an extremely small time frame.
QUANTUM COMPUTERS OVER CLASSICAL COMPUTERS
Any computational problem that can be solved by a classical computer can also be solved by a quantum computer. Conversely, any problem that can be solved by a quantum computer can also be solved by a classical computer, at least in principle given enough time.
Notably, quantum computers are believed to be able to quickly solve certain problems that no classical computer could solve in any feasible amount of time — a feat known as “quantum supremacy.”
QUANTUM SUPREMACY — A PHENOMENON YET TO BE ACHIEVED
Quantum supremacy is the point at which a quantum computer can complete a mathematical calculation that is beyond the reach of even the most powerful supercomputer. It is still unclear exactly how many qubits will be needed to achieve this because researchers keep finding new algorithms to boost the performance of classical machines, and supercomputing hardware keeps getting better.
THE CURRENT STATE OF QUANTUM COMPUTING
Right now, supercomputers can only analyze the most basic molecules. But quantum computers operate using the same quantum properties as the molecules they’re trying to simulate. They should have no problem handling even the most complicated reactions.
That could mean more efficient products — from new materials for batteries in electric cars, through to better and cheaper drugs, or vastly improved solar panels. Scientists hope that quantum simulations could even help find a cure for Alzheimer’s.
Most of the big breakthroughs so far have been in controlled settings or using problems that we already know the answer to. In any case, reaching quantum supremacy doesn’t mean quantum computers are actually ready to do anything useful.
Quantum computers will not wipe out conventional computers. Using a classical machine will still be the easiest and most economical solution for tackling most day-to-day problems. But quantum computers promise to power exciting advances in various advanced fields which are beyond the scope of a classical computer.
The disruptive growing potential of quantum technology will make the change of the internet era and make it look like a small bump in the road.
Quantum computers have the potential to benefit society in various ways, including making smarter investment decisions, developing drugs and vaccines faster, and revolutionizing transportation. This sustainable method will allow for improved research and development towards a cleaner future.
