US President Donald Trump signed a bill called the National Quantum Initiative Act to promote the development of quantum technology, with a 1$B funding quantum research.

European commission launched a work program clearly flagged on quantum technologies while Switzerland runs its own, federally funded NCCR-QSIT project. EPFL partnered with IBM, pioneer in this field with the IBM Quantum Experience (which I highly recommend to play with!), for teaching purposes. Microsoft invested in Quantum Computing lab at TU Delft.

China as well entered the race, investing billions in quantum tech and recently released a cloud platform for quantum computing.

Facts...

**So why does this “spooky” quantum tech draw such interest from companies and governments?**

First, because it is believed to be the **next revolutionary technology**, enabling so-called quantum computers running a million times faster than today’s fastest supercomputers.

Second, this power is expected to **break through nowadays biggest challenges** such as cryptography, machine learning, data analytics, chemistry calculations say for pharmaceutical applications and so on.

Third, as a consequence, quantum technology is full of business opportunities.

**What is quantum computing, in first the place?**

With quantum computing, we are plunging into the world of Infinitely Small, where the rules of classical physics cannot apply anymore. So forget about your usual 14nm transistors, it's too big already. We are now talking about electron-sized components.

While normal computers use bits (0 or 1), quantum computing uses qubits that can take both values (0 ** and** 1) at the same time, in any proportions: this is called

**superposition**.

So, while you can store only one value out of one bit (0 or 1), you can store two values in one qubit (0 ** and** 1). This grows exponentially as you add qubits, which allows 2N combinations at once. However (this is the tricky moment), as soon as you try to measure the qubit value, it collapses into a definite state...

Another property is the **entanglement**. It allows connecting two qubits: no matter how are far they are apart to each other, changing the state of a qubit instantaneously changes that of its partner. You can then deduce the properties of an entangled qubit by measuring its partner's state only.

Getting a result from a quantum computation involves using quantum gates that are different to our usual logic gates (AND, OR, NOT, and so on). While the logic gate outputs a definite answer, the quantum computations, using quantum gates, manipulates probabilities, entanglements and outputs a new set of superpositions (probabilities) that you can finally collapse into sequences of 0 and 1.

The nature of the qubits makes it possible to compute a huge number of combinations at the same time and getting the results. In other words, when a normal computer will try every single possibilities to run a simulation, quantum computers test all at once, reducing the computing time to the square root of a normal computer's. Quantum computers can analyze large quantities of data and spot patterns very fast.

**In practice?**

You can make qubits with semi-conductors but they require a specific environment: super cold temperature (close to absolute zero, or -273°C) to cool down the chips, and dust-free environment. You still need the hardware to control the qubits. A resonator is used to “read” the state of the qubits. It consists in using microwave pulses to manipulate the state, the information carried by the qubit. This requires to calibrate the microwave pulses so that we know exactly their properties, frequencies and duration in order to entangle qubits or flip the states. The key is to come up with algorithms where the result is deterministic.

Another big challenge in quantum research regards the coherence time. It is the amount of time for the qubit to retain its quantumness, that is to say that eventually, the energy will decay out of the qubit. In addition, the quantum error correction is under investigation.. Research teams all over the world are currently tackling these problems.

We humans have limited access to the universe, so quantum technology is not just a tool to build quantum computers but it is also a way to get to understand our environment, explore unresolved problems. Although it may not be intuitive, we should now take interest into this new technology that is expected to open new paradigms and opportunities (for quick introduction, I highly recommand to have a look at Kurzgesagt's video and PBS Infinite Series' video that beautifully shows the maths behind quantum computing).

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