Since the advent of powerful algorithms for quantum computation, we have been developing theoretical approaches for the physical implementation of these devices. We proved that two-qubit interactions are sufficient to implement any quantum algorithm, and introduced some of the initial ideas for what became known as NMR quantum computing. We then developed a set of five general criteria that have been very useful in guiding the search for a feasible quantum computing architecture. These five criteria say that for a system to be a candidate for an implementation of quantum computation, it should

1. Be a scalable physical system with well-defined qubits
2. Be initializable to a simple fiducial state such as |000...>
3. Have much longer decoherence times
4. Have a universal set of quantum gates
5. Permit high quantum efficiency, qubit-specific measurements

We have applied these criteria to develop a specific model for a solid state implementation, in which the qubits are represented by the spins of individual electrons trapped in an array of quantum dots. Initialization is accomplished naturally by cooling; decoherence times of electron spins in semiconductors are expected to be adequately long. Basic two-bit gates are accomplished by changing the height of the electrostatic barrier between quantum dots. Spin measurements are suggested in which the spin is converted into an electron position, which can then be measured directly. Many variants and embellishments on the basic idea are now being explored.

For papers on these subjects click here

Here is a link to my talk (June 2009) at the Nobel Symposium, Qubits for Future Quantum Computers

Here's my IEDM paper(12/2000)

Here's my recent (12/2000) IEDM talk