Monthly Archives: December 2015

…Quantum computers that is. They don’t quite exist yet (at least not at the level of practical use), but slowly mankind is working towards them. Here’s the story of why and how.

Actually, let’s preface this story with a quick overview of the switch that made modern computers possible; the switch, and amplifier, that’s known as a junction transistor. Before germanium-based (and later silicon-based) transistors, clunky, unreliable and energy inefficient vacuum tubes were used to close and manage circuits in televisions, radios, etc. Once transistors were invented in the late 1940’s, things started to change rapidly; suddenly transistors could be put in devices as small as hearing aides and pocket transistor radios became prevalent. Eventually people realized the transistor could be used in computers (making the 60,000 pound ENIAC the last of its breed), and they were so light, efficient and small that a whole world of more powerful computing opened up. Today, microprocessors are made with millions of transistors etched into their silicon wafers so that major computer processing can occur on handheld mobile devices.

Transistors have reigned for about 6 decades now… so what’s next? After all, according to Moore’s Law, the amount of transistors that can be fit onto a microprocessor should double approximately every two years. For this to remain true into the 2020’s and 2030’s, scientists are investigating the use of quantum computers, or computers whose processors and memory are managed at the level of atoms, ions, photons, and electrons (in this context they are called qubits). According to some scientific theories, the fact that these particles can exist in superposition (meaning that they would neither translate into a 0 or a 1) allows for a parallel processing power that could beat that of modern computers one million fold.

So how’s that coming? Well let’s follow the path of history:

los alamosIn 1998, Los Alamos and MIT researchers figured out how to spread a single qubit across three nuclear spins in each molecule of a liquid alanine or trichloroethylene solution. Researchers were able to use these solutions and the process of entanglement to figure out how to observe the qubit’s properties without corrupting it with the force of their attention.

In 2000, the scientists at Los Alamos hit it big again when they invented a 7-qubit computer that was contained within a single drop of liquid. This quantum computer used nuclear magnetic resonance (NMR) to manipulate particles in the atomic nuclei of molecules of trans-crotonic acid. The NMR was used for the application of electromagnetic pulses which forced the particles to all line up. These particles in positions parallel or counter to the magnetic field allowed the quantum computer to mimic the information encoding bits in digital computers.

stanfordIn 2001, researchers at Stanford University invented a quantum computer that could demonstrate Shor’s Algorithm (a method for finding the prime factors of numbers that plays a principal role in cryptography). The 7-qubit computer found the factors of 15.

Skipping forward to 2007, Canadian startup company D-Wave created a 16-qubit quantum computer that could solve a sudoku. D-wave’s most recent computing model the D-Wave 2X has over 1000 qubits, purportedly being able to find 2^1000 possible solutions simultaneously.