Viewing Quantum Computing Through a PLC Engineer’s Lens: From Digital I/O to “

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In traditional factory automation, electrical control engineers typically deal with two main types of signals:

• Digital Signals (D/I and D/O):
  For example, when a photoelectric sensor detects an object, the input is “1”; if it doesn’t, it’s “0.” A PLC’s logic program uses these on/off changes to decide whether to activate a relay. This is very much like the binary bits (0s and 1s) in a conventional computer.
  
• Analog Signals (A/I and A/O):
  Take a temperature sensor that outputs a voltage from 0 to 10V, corresponding to a temperature range of 0 to 100°C. This isn’t just two discrete states; it can be any value between 0 and 10V, giving you a continuous range instead of just a binary on/off.
  
  

Once we’re familiar with digital and analog signals, it might be easier to understand the concept of a quantum bit (qubit).

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From Digital to “Super-Analog”: The Superposition of Qubits
In the binary world, you’re limited to just two distinct states: 0 or 1, much like a digital input signal that’s either on or off. A qubit, however, can exist in a combination—“superposition”—of both 0 and 1 at the same time.
To illustrate:

• A digital bit is like having a voltage that’s strictly either 0V or 10V. No in-between.
• A typical analog signal can be any value between 0 and 10V, representing a single point along a scale.
• A qubit’s state is more like a point on the surface of a “two-dimensional sphere,” simultaneously containing components that correspond to both “0” and “1.” Instead of just one number, it involves “amplitude” and “phase,” adding a whole extra dimension of complexity.
  

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From Superposition to Measurement: Ultimately Still 0 or 1
While a qubit can hold “some of 0” and “some of 1” during computation, when you actually “measure” it, the result you get will still collapse to either 0 or 1.
The true power of quantum computing doesn’t come from directly seeing all possible values at once, but rather from using superposition to explore multiple paths in a calculation simultaneously.
Before you measure, you cleverly adjust the state to increase the odds that the answer you want will appear upon measurement.

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Conclusion: Understanding Quantum from an Automation Perspective


For engineers in automation and PLC environments, the quantum world may feel abstract. But using digital and analog concepts as a starting point, we can make a rough analogy:

• Digital signals: Binary, strictly 0 or 1.
• Analog signals: Continuous values, anywhere between 0 and 10V.
• Qubits: A “super-analog” state, able to represent both 0 and 1 at once before measurement forces it into one final outcome.
  

By thinking about qubits in this way, we can better appreciate their flexibility and potential. Although quantum computing is still evolving, it represents one of the most promising directions for the future of computation.