Quantum Adder

This is some simple quantum computing (IBM Qiskit and AWS Braket) code to add two two-bit numbers and get a three-bit result, in a way that can be run on a five qubit quantum computer or simulator. The current code adds 2 (0b10) and 3 (0b11) and should get 5 (0b101).

The adder is based on: Thapliyal, Himanshu & Ranganathan, N. (2013). Design of Efficient Reversible Logic-Based Binary and BCD Adder Circuits. ACM Journal on Emerging Technologies in Computing Systems (JETC). 9. 10.1145/2491682.

Getting started - on IBM Qiskit

To get this running, first install Qiskit

% pip3 install qiskit

and set up an account on IBM Quantum. Also ensure you have saved your API token.

Getting startups - on AWS Braket

To get this running, first install AWS Braket

% pip3 install amazon-braket-sdk

and ensure you have already configured an AWS account and installed the CLI tools.

Running the code

There are two version of the code for each of Qiskit and Braket:

1. add.py (or add_aws.py) runs the addition in the simulator
2. addcloud.py (or addcloud_aws.py) runs the addition in a cloud-based quantum computer (by default, on the five qubit Belem system on Qiskit or the 34 qubit SV1 simulator on Braket) They all work the same way - just run them like this:

% python3 add.py
           ░                                          ░          
q_0: ──────░─────────────■──────────────■────■────────░──────────
     ┌───┐ ░           ┌─┴─┐          ┌─┴─┐  │        ░          
q_1: ┤ X ├─░───■────■──┤ X ├──■────■──┤ X ├──┼────■───░──────────
     ├───┤ ░   │    │  └─┬─┘  │    │  └─┬─┘┌─┴─┐  │   ░ ┌─┐      
q_2: ┤ X ├─░───┼────┼────■────┼────┼────■──┤ X ├──┼───░─┤M├──────
     ├───┤ ░ ┌─┴─┐  │         │  ┌─┴─┐     └───┘┌─┴─┐ ░ └╥┘┌─┐   
q_3: ┤ X ├─░─┤ X ├──┼─────────■──┤ X ├──────────┤ X ├─░──╫─┤M├───
     └───┘ ░ └───┘┌─┴─┐     ┌─┴─┐└───┘          └───┘ ░  ║ └╥┘┌─┐
q_4: ──────░──────┤ X ├─────┤ X ├─────────────────────░──╫──╫─┤M├
           ░      └───┘     └───┘                     ░  ║  ║ └╥┘
c: 3/════════════════════════════════════════════════════╩══╩══╩═
                                                         0  1  2 
Compiled circuit depth = 9

Total counts are: {'101': 1000}

You can see that it has run 1000 times, and every time it has come up with the right answer of 2 + 3, i.e. 5 (0b101).

The AWS Braket one looks a bit different, but essentially the same:

% python3 add_aws.py
T  : |0|1|2|3|4|5|6| 7 |

q0 : -------C-----C-C---
            |     | |
q1 : -X-C-C-X-C-C-X-|-C-
        | | | | | | | |
q2 : -X-|-|-C-|-|-C-X-|-
        | |   | |     |
q3 : -X-X-|---C-X-----X-
          |   |
q4 : -----X---X---------

T  : |0|1|2|3|4|5|6| 7 |
Compiled circuit depth =  8

Total counts are: {'101': 1000}

The addcloud.py (and addcloud_aws.py) version will take longer to run as it is executing on a real quantum computer somewhere, which might take a while if that quantum computer has a lot of compute jobs queued up. It will also return a range of counts due to the noise inherent in a real quantum computer, so the code will pop up a histogram at the end to make it easier to understand. The histogram from a real quantum computer will look something like this: or like this: