A team comprised of researchers from the University of Chicago and Argonne National Laboratory are hoping to prove that aluminum nitride will provide a less expensive alternative to diamonds when creating qubits.

### Qubits 101

Quantum bits, or qubits for short, are the key to quantum computing’s processing power.

Data is transmitted via bits (short for “binary units”), represented as 1s and 0s. Qubits (short for "quantum bits"), however, are a third bit value that occur in a state known as superposition of the binary bit values.

In quantum physics, superposition occurs when a particle is in two quantum states at once. For computing purposes, this means that information could be transferred as a 1, a 0, or a third state, superposition, that is both 1 and 0 simultaneously.

*A representation of a qubit. Image courtesy of the University of Strathclyde.*

Currently, qubits are created by exploiting a naturally-occurring defect in diamonds at the atomic level.

### Creating Qubits with Diamond

We know that qubits can be created using diamonds that have a nitrogen vacancy (NV) within it. A nitrogen vacancy is an impurity in a diamond's crystalline structure which can occur in nature. The process of creating a qubit in this environment involves placing strain, via driving fields, on the atomic structure of the nitrogen vacancy system.

*Graphical representation of the qubit creation process using diamonds. Image courtesy of the American Physical Society.*

Researchers at MIT have been experimenting with synthetic diamonds for years, engineering nitrogen vacancies that mimic those that occur in nature. They continue their work to stabilize superposition in these synthetic diamonds so that quantum entanglement can be achieved.

### Aluminum Nitride as an Alternative to Diamond

The team from the University of Chicago and Argonne National Laboratory believes that these techniques can also be used when using aluminum nitride instead of synthetic diamond.

One of the benefits of substituting aluminum nitride for diamond is that it's already a popular material available to many labs across the globe.

Aluminum nitride is a semiconducting material and is frequently used in optoelectronics. It is used in MEMS (microelectromechanical systems), layered between metals for use in devices like RF filters. It’s also used in the fabrication of nanotubes and ultraviolet light-emitting diodes.

*Aluminum nitride substrates wafers. Image courtesy of Valley Design Corp.*

Aluminum nitride is an ionic crystal, which makes it a prime candidate for replacing diamonds in the creation of qubits.

Like with synthetic diamond, piezoelectric aluminum nitride, when placed under strain, can generate a defect similar to the ones that facilitate the creation of qubits in diamond.

Now that the team has identified aluminum nitride as a possible material for creating qubits, they’ll need to do laboratory testing to confirm their calculations.

If aluminum nitride meets its potential in creating qubits, quantum computing may be more accessible than previously thought. Aluminum nitride provides a significantly less expensive material for qubit creation, which means that quantum computing research could be done realistically in more labs.

1 CommentLogintonyr10842016-06-10Not that I know much about this stuff, if digital has 0’s and 1’s, how is a “Half-Zero/Half-One” going to be used? What’s the benefit? Please explain.

Kate Smith2016-06-10Hey Tony, thanks for the comment.

Here’s my understanding: Qubits are useful in quantum computing because they allow for techniques like superdense coding, where qubits can actually hold more information than a classical bit can. The reason for this is essentially mathematical.

Two bits can be described by two values, either a 1 or a 0 (representative of the up or down spin of a particle, respectively).

By comparison, qubits have a probability of being in a 1 or 0 state. So they require more information to describe their state compared to a classical bit. For each qubit, you need to know the coefficient value that describes its probability of being a 1 and the coefficient value that describes its probability of being a 0.

So here’s my takeaway in its simplest form: Two bits can be described by two values. Two qubits need to be described by four values. That means that you get four values, four pieces of information, in two qubits.

Here are a few resources:

-https://www.youtube.com/watch?v=g_IaVepNDT4

-http://www.allaboutcircuits.com/technical-articles/basic-analysis-of-a-quantum-processors-components/

-https://www.cl.cam.ac.uk/teaching/0910/QuantComp/notes.pdf

Thanks for reading, Tony!