Sandia National Laboratories has taken a first step toward creating a practical quantum computer, able to handle huge numbers of computations instantaneously. A "donor" atom propelled by an ion beam is inserted very precisely in microseconds into an industry-standard silicon substrate. The donor atom -- in this case, antimony (Sb) --carries one more electron (five) than a silicon atom (four). Because electrons pair up, the odd Sb electron remains free. Instruments monitor the free electron to determine if, under pressure from an electromagnetic field, it faces up or down, a property called "spin."
A study to prod an antimony nucleus (buried in the middle of this device) with magnetic fields became one with electric fields when a key wire melted a gap in it. An accidental innovation has given a dark-horse approach to quantum computing a boost. For decades, scientists have dreamed of using atomic nuclei embedded in silicon--the familiar stuff of microchips--as quantum bits, or qubits, in a superpowerful quantum computer, manipulating them with magnetic fields. Now, researchers in Australia have stumbled across a way to control such a nucleus with more-manageable electric fields, raising the prospect of controlling the qubits in much the same way as transistors in an ordinary microchip. "That's incredibly important," says Thaddeus Ladd, a research physicist at HRL Laboratories LLC., a private research company.
Researchers at Princeton University have made an important step forward in the quest to build a quantum computer using silicon components, which are prized for their low cost and versatility compared to the hardware in today's quantum computers. The team showed that a silicon-spin quantum bit (shown in the box) can communicate with another quantum bit located a significant distance away on a computer chip. The feat could enable connections between multiple quantum bits to perform complex calculations. Princeton scientists demonstrate that two silicon quantum bits can communicate across relatively long distances in a turning point for the technology. Imagine a world where people could only talk to their next-door neighbor, and messages must be passed house to house to reach far destinations.
The high technological and strategic stakes mean major technology companies as well as ambitious start-ups and government-funded research centers are all in the race to build the world's first universal quantum computer. In contrast to today's classical computers, where information is encoded in bits (0 or 1), quantum computers process information stored in quantum bits (qubits). These are hosted by quantum mechanical objects like electrons, the negatively charged particles of an atom. Quantum states can also be binary and can be put in one of two possibilities, or effectively both at the same time--known as quantum superposition--offering an exponentially larger computational space with an increasing number of qubits. This unique data crunching power is further boosted by entanglement, another magical property of quantum mechanics where the state of one qubit is able to dictate the state of another qubit without any physical connection, making them all 1's for example.
Although quantum computing is still in its infancy, enough progress is being made for it to look a little more promising than other "revolutionary" technologies, like fusion power or flying cars. IBM, Intel, and Google all either operate or are producing double-digit qubit computers right now, and there are plans for even larger quantum computers in the future. With this amount of inertia, our quantum computing revolution seems almost certain.