Computing at the atomic scale

Imagine a computer that can manipulate and process exponential sets of inputs simultaneously. Such a computer could break today’s encrypted codes and search large databases in a fraction of the time it takes for a conventional computer to execute the same task. Srikanth RP elaborates on how quantum computers could turn computing upside down

Conventionally computers have always represented data in the form of bits which exist in two states, zero or one. A bit is thus the fundamental unit of information in a conventional computer. However, a quantum computer’s lowest fundamental unit of representation is called the Quantum bit or the ‘Qubit’ and it is represented by an atom in one of two different states, which can also be denoted by a zero or one. But unlike the normal bit, a qubit can exist simultaneously in not only its individual states (either 0 or 1) but also each qubit can share its states with every other qubit. This means that while two qubits can represent or store only two pieces of information, their shared states can store four pieces of information at the same time. This advantage increases exponentially as the number of qubits rises. The basic formula for representing qubits is 2^n – n denoting the probability for the number of states data can be represented. For example, a two qubit quantum computer can handle four states. This ability of the quantum computer to act on all its multiple states simultaneously makes it immensely powerful when compared to a conventional computer. Hence, a quantum computer can perform big operations in parallel using a single processing unit.

Beyond Moore’s law

Moore’s law states that the number of transistors on a microprocessor doubles every 18 months. While today’s technology allows extremely small logic gates to be punched onto the surface of silicon chips – this method of creating processors which are increasingly becoming smaller and more powerful is expected to hit a barrier. Analysts believe that if the industry has to keep in pace with Moore’s law, circuit features would have to be the size of atoms and molecules. However, by using atoms and molecules as the basic elements of quantum computers, the power of computing can be scaled to an exponential level.

Some applications for quantum computers

The interest for developing quantum computers has mushroomed keeping in mind its potential for solving difficult computing tasks such as searching large databases or factoring large numbers. Similarly encryption and decryption is a practical application that can be optimised by deploying quantum computers.

Practical quantum computers could make many of today’s encryption standards obsolete. Current data encryption and advanced encryption standards are based on levels of computational difficulty. The codes are not impossible to break, but they are next to impossible to crack within a reasonable amount of time using conventional resources. For example, most of today’s encryption standards are based on the notion that encrypted data takes millions of years of computer processing time to be decrypted without the proper key. If quantum computers hit the street, with the enormous boost in computing power that they promise, today’s encryption standards will be in danger. For example, for a 400 digit number, it would take a billion to 10 billion years for a supercomputer using conventional algorithms to factor that number. A quantum computer can do this in a few months.

If quantum computers are made available, massive changes would need to be made to today’s encryption standards. However, the same quantum computers can also be used to develop some very advanced systems. In fact, IT companies believe that a product that provides perfect encryption can be developed using quantum computing principles.

From theory to practice

While interest in quantum computing has mushroomed over the last decade, building a quantum computer in real life has proved to be extremely difficult and the successful experiments are few and far between. One of the primary reasons for this has been the fact that operating on an atomic scale as a quantum computer does, getting the atoms to behave as one wants is mighty difficult. Additionally, the quantum states of atoms and subatomic particles that quantum computer prototypes use to represent the zeros and ones are so fragile that energy from small amounts of light, heat and

magnetism can wipe out the information that they hold. Researchers are working on creating safe environments where the quantum bits can function effectively.

While most current research in quantum computing is still theoretical, researchers believe that the day when quantum computers will replace silicon chips is not far, just like the transistor once replaced the vacuum tube. When that happens, expect a quantum leap in computing.

srikanth@expresscomputeronline.com