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Quantum Supremacy by Google. Explained in Easy way.


This article has discussed the following points,

  1. What does quantum supremacy mean?
  2. Some fundamentals to understand quantum supremacy.
  3. When we can say that quantum supremacy has been achieved.
  4. “Sycamore” a Quantum Processor.
  5. What helped google to achieve quantum supremacy.
  6. What does the future hold?

1. What does quantum supremacy mean?

In the most simple and famous definition,

“ Quantum supremacy is that moment when a quantum computer beats the best supercomputer in solving some kind of problem.”

2. Some fundamentals to understand quantum supremacy.

To understand quantum supremacy we need to understand quantum computing and to understand quantum computing we need to understand quantum computers and to understand the difference between quantum computers and classical computers we need to know some basic concepts of the two.

Classical computers(phones, laptops, and tablets, etc) works on classical binary bits i.e 0 or 1. Like two sides of the coin, either heads or tails. In a similar way, classical computers have to make their decision between either 0 or 1. But quantum computers works on QUBITS(quantum bits) and QUBITS are pretty much different than classical binary bits. 1 qubit has the ability to store the information in both 0 and 1 at the same time. That means if you have 2 QUBITS then you can store 2^10 = 1024 possible states of information and as it gets increasing the possible states get increasing exponentially. So we can see that quantum computers are fundamentally different than classical computers and they are not at all comparable.

3. When we can say that quantum supremacy has been achieved?.

As stated above

“ Quantum supremacy is that moment when a quantum computer beats the best supercomputer in solving some kind of problem.”

In the abstract of their research paper released by Google in August 2019 said,

The tantalizing promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor. A fundamental challenge is to build a high-fidelity processor capable of running quantum algorithms in an exponentially large computational space. Here, we report using a processor with programmable superconducting qubits to create quantum states on 53 qubits, occupying a state-space 253 ∼ 1016. Measurements from repeated experiments sample the corresponding probability distribution, which we verify using classical simulations. While our processor takes about 200 seconds to sample one instance of the quantum circuit 1 million times, a state-of-the-art supercomputer would require approximately 10,000 years to perform the equivalent task. This dramatic speedup relative to all known classical algorithms provides an experimental realization of quantum supremacy on a computational task and heralds the advent of a much-anticipated computing paradigm.”

Google demonstrated quantum supremacy in three steps:-

  1. i) Pick a circuit.
  2. ii) Run it on the quantum computer.
  3. iii) Simulate what the quantum computer is doing on a classical computer.
  4. iv) And gradually increase the complexity of the circuit and then at some point it becomes impossible for classical computers to keep up.


“And quantum supremacy has been achieved”

4. “Sycamore” a Quantum Processor.


They designed a quantum processor named “Sycamore” which consists of a two-dimensional array of 54 transmon qubits, where each qubit is tunably coupled to four nearest-neighbors, in a rectangular lattice. The connectivity was chosen to be forward compatible with error correction using the surface code. A key systems engineering advance of this device is achieving highfidelity single- and two-qubit operations, not just in isolation but also while performing a realistic computation with simultaneous gate operations on many qubits.

“FOOOOO!!!This took me a while to understand!!”

But A physicist Mr. John Martin easily explains  “The processor that reached quantum supremacy is called “Sycamore Processor“. It can do the parallel processing up to 54 qubits that is 2^53 states which are 10 million billion and thus this enormous amount of parallel processing gives it the power”

5. What helped google to achieve quantum supremacy?.

  1. The enormous amount of experimental data.
  2. Computational power has been hugely upgraded and compact which makes this possible.
  3. Quantum chips and the infrastructure that you need to drive those chips.
  4. Cryostats and software.
  5. And not forgetting the TEAM of humans.

6. What does the future hold?

There was a time when intel processors also created history when they released their own processors. And some way or another all the revolution becomes mainstream in the end. Since google achieved it first(as they say) future is bright because humans are the species that can do unbelievable things in unbelievable ways and this would be one of the catalysts that make this easier.