Which high impedance / differential probe can be used with the E5052A/B Signal Source Analyzer?

As for the high impedance probe, the 54006A passive divider probe is recommended.

54006A Resistor Divider Probe
Up to 6 GHz
Zin = 500 Ω (10:1)
Zin = 1 kΩ (20:1)

When Zin of the 54006A is not enough high for the customer's application, 41800A will be the solution.

41800A Active Probe
5 Hz - 500 MHz
Zin = 100 kΩ (probe alone)
Zin = 1 MΩ (with 10:1, 100:1 divider)

As for the differential probe, the U1818A/B is applicable; U1818A covers up to 7 GHz, U1818B is up to 12 GHz.
Also, the 1134A InfiniiMax 7 GHz Probe System can be used. To use the 1134A, we also need to use an adaptor and power supply for the adaptor.

1134A InfiniiMax 7GHz Probe System
N1022A Probe Adaptor
1143A Probe Power

When you use the probe, please note the following limitations.

1. Probe has some insertion loss that depends on Zin. The output power level of the probe should be within RF IN measurement level of the E5052A/B. It is -20 dBm to + 20 dBm (> 30 MHz), -15 dBm to +20 dBm (< 30 MHz).
2. The noise measurement sensitivity will be limited by the additive noise from the active probe. This noise is not reduced by the cross-correlation technique. The nominal noise floor of the active probe is -140 dBm/Hz to -150 dBm/Hz. When the signal power level is low, check the target noise level and note this limitation.
3. Spurious will be generated by the probe. For the Random jitter (RJ) measurement, the SSA can calculate the RJ omitting spurious.