Quantum Networks: question bank

Q1

FoundationCore practice

What does a quantum network use to connect distant quantum computers?

Your answer

Q2

FoundationCore practice

Which particle is most commonly used to carry quantum information across fiber optic cables in quantum networks?

ElectronsPhotonsProtonsNeutrons

Q3

FoundationCore practice

What is the main purpose of a quantum repeater in a quantum network?

To amplify quantum signals like a classical amplifierTo create fresh entanglement across long distances using entanglement swappingTo convert quantum signals into classical signals and backTo store quantum information indefinitely in memory

Q4

FoundationCore practice

What happens to a quantum state if you try to measure it to check for eavesdroppers?

It stays exactly the sameIt collapses randomly to one definite outcomeIt becomes stronger and easier to detectIt splits into two copies automatically

Q5

FoundationCore practice

Calculate how many times farther a signal can travel if a quantum repeater station is placed every 50 km instead of every 10 km, assuming you need to cross 500 km total. How many fewer stations are needed?

Your answer (stations)

Q6

FoundationCore practice

In entanglement swapping, if Node A is entangled with Node B, and Node C is entangled with Node D, what measurement allows B and C to become entangled instead?

Your answer

Q7

FoundationCore practice

What theorem of quantum mechanics prevents you from simply copying an unknown quantum state to boost a weakening signal in a network?

Your answer

Q8

FoundationCore practice

A quantum network needs to send a 256-bit cryptographic key using BB84 quantum key distribution. Roughly how many photon pulses must be sent if, on average, half are lost in transmission and another half are discarded due to wrong basis measurement?

Your answer (pulses)

Q9

FoundationCore practice

What does a quantum node typically contain in a quantum network?

a) Only classical computer servers b) A quantum processor paired with classical control systems c) Solar panels for energy harvesting d) Standard Wi-Fi routers

Only classical computer serversA quantum processor paired with classical control systemsSolar panels for energy harvestingStandard Wi-Fi routers

Q10

FoundationCore practice

Bell-state measurement is a key operation in quantum networks. What does it actually measure?

a) The speed of photons traveling through fiber b) The polarization angle of a single photon precisely c) Whether two photons are in one of four specific maximally entangled states d) The temperature of a quantum repeater

The speed of photons traveling through fiberThe polarization angle of a single photon preciselyWhether two photons are in one of four specific maximally entangled statesThe temperature of a quantum repeater

Q11

FoundationCore practice

Suppose a quantum network has quantum repeaters every 100 km, and the maximum distance photons can travel without a repeater is 100 km. What is the maximum total distance between the two end nodes if there is 1 repeater placed in the middle?

Enter your answer in kilometers.

Your answer (km)

Q12

FoundationCore practice

In a quantum memory, what is stored?

a) Classical bits like 0s and 1s from the internet b) Photons in a superposition or entangled state for later use c) Electrical charge from solar panels d) Backup copies of quantum states

Classical bits like 0s and 1s from the internetPhotons in a superposition or entangled state for later useElectrical charge from solar panelsBackup copies of quantum states

Q13

FoundationCore practice

Why can't you just use a classical amplifier (like in ordinary fiber optic networks) to boost a weakening quantum signal?

a) Classical amplifiers are too expensive b) They require too much electricity c) Measuring the quantum state to amplify it destroys superposition and entanglement d) They work perfectly fine for quantum signals

Classical amplifiers are too expensiveThey require too much electricityMeasuring the quantum state to amplify it destroys superposition and entanglementThey work perfectly fine for quantum signals

Q14

FoundationCore practice

A quantum network uses wavelength division multiplexing (WDM) to send many quantum signals through one fiber. If each channel needs 0.1 nm of spectrum and the total available spectrum is 10 nm, how many quantum channels can the fiber support?

Enter your answer as a whole number.

Your answer (channels)

Q15

FoundationCore practice

What is entanglement distribution in a quantum network?

a) Sending classical emails about quantum physics b) Creating pairs of entangled particles and delivering one to each distant node c) Shipping quantum computers through the mail d) Broadcasting the same quantum state to many receivers

Sending classical emails about quantum physicsCreating pairs of entangled particles and delivering one to each distant nodeShipping quantum computers through the mailBroadcasting the same quantum state to many receivers

All 61 questions