3.4 KiB
D-Wave's 2019 Recap
D-Wave is one of the first quantum computing companies based in Canada to actively work on developing a quantum processing chip for future computation applications. In May 2019, they hosted a webinar that summarized their quantum developments up until that point. I've summarized some of their main takeaway points below.
Simulating Physics with a Computer
So what is a qubit?
A qubit is not a physical thing in nature but rather a mathematical model. Essentially, anything that vibrates in nature acts as a harmonic oscillator function, or behaves as a wave. /include wave image here. A system with two energy levels is a qubit and their system of simulating these qubits is by creating a superconducting loop with two currents on either side. There's also the method for trapped ion chips to emulate qubit system as well that are being worked on.
There are even interesting developments to explore qubit systems through mapping topological matter which is done by braiding patterns of particles as they move though space & time.
Essentially, creating the physical qubit system is an engineering choice. This can be analagous to the classical computer being built through vacuum tubes. The qubit itself is a mathematical model of a simulated wave with two energy levels.
Standard Model of Quantum Computing
Gate/Circuit Model
How do you read a circuit model?
- horizontal lines in the circuit model = the amount of qubits in the system
- A system composed of multiple qubits thus explodes exponentially
- if you have n qu bits —> vectors of 2^n
n qubits = 2^n vectors
Hence, the wave function of a nine qubits system would mean
2^9 = 512
Hence, each gate acts on this wav function as a unitary matrix of size 512 x 512. Next, these measurements projects the vector onto a subspace. In the end, 1 final vector is outputted and some measurements will be made on this.
Peter Shor made the discovery that factoring integers can be combines quickly with the Quantum Fourier Transform (QFT)
You can factor quickly and efficiently using Shor's Algorithm now! However, quantum theory was still abstract back in 1994 but theoretically, since modern computers use the difficulty of factoring for its encryption foundation, a key mathematical concept was introduced.
Quantum Computing now being researched heavily. However:
Problem: The waves & noise associated with quantum measurements
The coherence property of waves is leading many researchers into having issues with its stability.
Explanation: At it's highest or lowest points when two waves come together and interfere with each other, one of two things occur:
- constructive interference: two interacting waves enforce each other
- destructive interference: two interacting waves destroy each other
In Shor's algorithm, this is still considered as numbers are accounted for to enforce or destroy. However, even still the issue of noise is still apparent in the waves.
Explanation: the analogy of an actual ocean wave can be considered. When several waves crash into each other, there will be many ripples. Hence if you add more ripples to waves, it is possible to swamp the waves entirely.