A scanning tunnelling microscope image showing the electron wave function of a qubit made from a phosphorus atom precisely positioned in silicon. Scientists from the University of New South Wales (UNSW) have announced making two atom quantum bits (qubits) "talk" to each other in silicon, providing the ability to see their exact position in the solid state. The team, led by Director of the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) -- and recent recipient of the Australian of the Year award -- UNSW Professor Michelle Simmons, created the atom qubits by precisely positioning and encapsulating individual phosphorus atoms within a silicon chip. The information is stored on the quantum spin of a single phosphorus electron, the university said. "In placing our phosphorus atoms in the silicon to make a qubit, we have demonstrated that we can use a scanning probe to directly measure the atom's wave function, which tells us its exact physical location in the chip.
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.
The University of New South Wales (UNSW) has announced the demonstration of a compact sensor for accessing information stored in the electrons of individual atoms, touted as a breakthrough that brings a scalable quantum computer in silicon one step closer. UNSW is banking on silicon being the key to building the first quantum computer and the results of the research, conducted within the Professor Michelle Simmons-led Simmons group at the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), show how this may be achieved. Quantum bits (qubits) made from electrons hosted on single atoms in semiconductors is a promising platform for large-scale quantum computers, the university believes, and creating qubits by precisely positioning and encapsulating individual phosphorus atoms within a silicon chip is the approach Simmons' teams are taking. Read also: Australia's ambitious plan to win the quantum race However, adding in all the connections and gates required for scale up of the phosphorus atom architecture was the challenge the researchers were faced with. "To monitor even one qubit, you have to build multiple connections and gates around individual atoms, where there is not a lot of room," Simmons said.
Engineers at the University of New South Wales (UNSW) have announced the invention of a "radical" architecture for quantum computing, essentially allowing quantum bits (qubits) -- the basic unit of information in a quantum computer -- to be placed hundreds of nanometres apart and still remain coupled. The invention is based on novel "flip-flop qubits" that UNSW said promises to make the large-scale manufacture of quantum chips dramatically cheaper and easier. To operate the flip-flop qubit, researchers need to pull the electron away from the nucleus, using the electrodes at the top; doing so creates an electric dipole. The conceptual breakthrough is the creation of an entirely new type of qubit using both the nucleus and the electron. The new chip design allows for a silicon quantum processor that can be scaled up without the precise placement of atoms required in other approaches.
Here we discussed the advantages and limitations of seven key qubit technologies for designing efficient quantum computing systems. The seven qubit types are: Superconducting qubits, Quantum dots qubits, Trapped Ion Qubits, Photonic qubits, Defect-based qubits, Topological Qubits, and Nuclear Magnetic Resonance (NMR) . They are the seven pathways for designing effective quantum computing systems. Each one of them have their own limitations and advantages. We have also discussed the hierarchies of qubit types.