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Simulation of Quantum Computation

Welcome to Squankum

Currently Squankum lets you :

  • Visualize a single qubit
    • Observe graphically the representation on a Bloch Sphere
    • Observe the relationship between the Bloch angular representation and spinor notation
  • Perform single-qubit operations
  • Observe representation of two coupled qubits (not fully implemented)


Hadamard operation on a single qubit.

Hadamard operation screenshot

  • The qubit's state is represented as the yellow vector on the Bloch Sphere.
  • It is expressed mathematically through the two angles theta/phi, or as the 2-element complex spinor below.
    • Relative probabilities for finding the qubit in state |0> and |1> are shown to the right of the spinor
  • Sliders for theta / phi on the input qubit can be dragged, updating the input/output qubits in real time
    • A slider for an overall phase is supplied. This doesn't affect the vector, but scales the spinor by exp^(i phase). The qubit's state is invariant to this overall phase.
  • Other single-qubit operators can be chosen from the drop-down menu
  • The viewing angle can be adjusted through the alpha/beta/gamma sliders, which are implemented as Eulerian angle rotations

History of Squankum

In 2003-2004 I developed an interactive Quantum Computation applet, as part of my Technology Fellowship from the Johns Hopkins Center for Educational Resources. There was a fair amount of interest in this project, so in 2007 I renamed it as Squankum, and released the source code as Free Open Source Software under the GNU Public License.

Why did you choose the name Squankum?

Firstly, Squankum sounds cool, something roughly like an abbreviation for Simulation of Quantum Computation.

But more realistically, Squankum is an old name for a town nearby Freehold, New Jersey where I grew up. Squankum itself is a name in the Algonquian language meaning "Place of Evil Ghosts", given to the area by the Native American Lenni-Lenape tribe. They were possibly referring to the mosquitos.


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